Pond Skipper

Yea I think so too, I have never had a square nitro engine other than big bird gasoline engines.

aspeed

Wow, 1000 replies to one plane. Guess I should show a pic for a reason to type something. Round Turbo head that matches the square fins on the ASP .15. You can grind and file the fins on the motor where the exh is in the way. I kind of like the Evo fins.

Pond Skipper

Well this was the 1/2A Skorch thread but then it turned into the Skorch II thread
I also post as my general hang out thread for engine conversions and various procured types.


The turbo head effort looks good Alan. I only have the AP .09 that is fin less at the moment.
Yea I like the evolution fins fancy sweepy aerodynamic efforts.

Pond Skipper

The beast is squared off and looking feisty

The bottom fin is cut darn near up against the round portion of the head / sleeve footing
which ultimately controlled the size of the square any closer could damage the anodizing.
Just the engine and spinner nut 164g

combatpigg

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That worked out good..!
This sort of stuff is more interesting than looking at the usual engine reviews in magazines.

Pond Skipper

Yes its been another enjoyable conversion project that panned out as buying on ebay can be risky when it comes to engines.You just don't know till you have it opened up and checked out what you are really getting.

Here is one with the pipe installed all up weight now is 208g

dwaynenancy

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Would someone direct me to the place where I could receive plans for the plywood fuse? Thank you.

aspeed

That looks pretty good. I think those 1/2 wave car pipes might make good power if you start out with a really long piece of tubing, and shorten it as required for your selected prop. I have been thinking of those for some other projects. Some of the .21 size ones look pretty useful, and are sometimes less than $10. I have seen some steel ones that are really quite light. The aluminum ones are normally a bit thicker and end up at the same weight. Maybe some scores could be had from the racers who go with the "pipe of the week" club. To get back to the fins, the old S Tiger X .15 fins were thin at the front and thicker at the back presumably to cool the exhaust half of the cylinder. The older G .15 had fins on only the exhaust side of the head too. Some stunt guys were putting an air dam on the outside of the fins to cool more evenly. They were just beer can metal with wire holding them on. The opening was a bit bigger on the front. They run for a fairly long time and have cowls, so heat was often a problem. I made one up for a Foxberg racer once, and was outlawed. I thought maybe it would streamline it a little too.

Pond Skipper

Dwayne there are no plans, this thread starts as a design build for a 1/2A Skorch and now this newer version Skorch II for strong .061 thru .09 engines:

Link to the 2nd build within the thread does post some clear pics of the pattern with a yard stick next to it for size reference.

Skorch II starting at post #649
http://www.rcuniverse.com/forum/1-2-...l#post12071772

Pond Skipper

Thank you for sharing Alan, could round the front end to a half moon shape leave the back square with fins.

The car pipe really goes with the Sportwerks .05 with header shown less about 1" of the curved down section. As shown it should do very well with the 4.2x4 at 28k. There are some real nice car pipes for cheap and some not so cheap.

The MAC pipes are like 29 bucks on eBay.
The outrigger guys use them with the .12's and set from 9" to 10" from middle of the divergent cone. Some prefer to set at the apex between the divergent and convergent cones to piston face. Others say go from the center of the piston, really down to tuning with your tach till your happy.

Since I want wide open top end I have the pipe at 8" from the center of the divergent cone. 35 to 36k unloaded is the goal well within the manufactures practical rpm limit of 41k.

Comparing .05 /.12 engines with props and spinners less pipes: 74g vs172g

Pond Skipper

Aileron servo mounted and setup with dual rates, added the neon yellow on the wing was the original plan but was liking the solid blue for a week. The wing wasn't matching the horizontal stab so finally got around to adding it for the maiden flight Sunday. Time to charge everything up and ream out a few spare props and set up the flight box for this plane.

Mr Cox

The plane looks great, good luck on the maiden!

Is that a sliding carb on the .12 engine?

My Picco .12 was a little hard to tune with the sliding carb, rich middle range and lean high end, perhaps I didn't have enough tank pressure at full throttle. I swapped it out for an MDS .18 carb and got the same top end but better throttling in the midrange.

Here are some numbers on the bench, running an APC 7x4 prop and 10%nitro;
MVVS "tuned" muffler 4000-18900rpm (I think these are only tuned for 19000rpm)
Rossi (I think) .15 tuned pipe; 22000rpm (the length is fixed, there might be more here by trying different props)

I'm liking this engine more and more, powerwise it is very close to a regular .15 air plane engine, but handling is much better. It seems to take high revs at ease and will idle at around 4-5000rpm immediately after an extended run at full throttle.

Pond Skipper

Thank you Kris will post a vid or two will maiden with the 5x3 for good thrust to get the plane up and away from the ground to fix in the trims.The extra weight of the .07 ended up throwing my CG off some that and going with swept back leading edge on the wing I ended adding 12g of lead in the tail. Had I used the .05 engine lead wouldn't have been needed but at a big loss in power. With a full tank it will be a bit nose heavy on launch. I used two separate chucks of lead in hopes I can remove one after trims have been sorted out.


Yes the V12RR is a sliding carb too. There is a advantage of a full unrestricted opening air intake much increased over most barrel types that tend to have a undersized bore. So pressure is required to keep up with the additional air. I will use nyrod and cable with a small bracket to guide the nyrod to curve so the cable goes around the front face of the engine. I see you like the 7x4 I want to keep the rpm up at 35k -36k I think my perfect prop will be a 6x5 trimmed tips from a APC 6.5x5 and will use 35% nitro custom blend 12% castor 10% synthetic.


The Vertigo has a low end needle with a barrel carb it took some adjusting to get the mixture transition to not load up low / mid or high. You have to adjust and wait for change before adjusting again till the desired effect is found. The .07 car engine will drop down to a nice idle every time like clock work it is reliable and should leave less fear of a flame out when flying. I reworked the venturi and polished it after testing saw a good jump in rpm and had to rich up the mixture some to compensate for the extra air. Throttle response is impressive these car engines do like rpm and are made to handle it.

Mr Cox

I used the APC 7x4 mainly as a standard to compare with data from other .12 and .15 engines. In terms of load I think it is a little higher than the APC 6.5x5 which has very narrow blades. I need to ream out some more props to try with next time. As a comparison the ASP .12 spins the 7x4 at around 17000rpm.

There seems to be an error in the APC data file though, I'm guessing it is close to 0.5hp in power but the file from APC says 1.1hp... ? http://apcserve.w20.wh-2.com/v/PERFI...B/PER3_7x4.dat

aspeed

I used the 7-4 as a standard as well, because that is their recommended one. I used the MA brand, as it is more available here, I think the static numbers are about the same as APC, but flying the APC may be faster. The FP .10 was 17,500, LA 18,000 (with a .005" shim) 17,500 with the thicker stock one. The AP .09 16,900, and the TD .09 16,400 (it had a muffler, the others did not.) My Picco .12 which is not broken in, but seemed fitted about right from the box used a 7-5 MA prop and gave better results at 18,300 and 22,000 with a pipe. I found the extra inch of pitch is about 3,000 rpm, so the Picco is kind of magic. I would guess some other newer car motors could match that. Whew, so many numbers. Seems like the ASP .12 and their AP .09 are about the same then. I don't need to buy one then.

Pond Skipper

Nitro content makes a difference along with air temp.
It takes more power to reach 19k in colder dense air than a prop moving in warm air.

The V12RR manufacture states 1.4hp at 41k I think they use 40% nitro
Second party engine reviewer who does dnyno tests on many car engines stated 1.25hp at 41k
The ASP .12 had / has versions as a car engine, boat engine and aero engine. As a .12 it
was made for rpm. Chuck had his engine propped for rpm and it performed well hitting 29k
in dives, level flight was 27.5 thru 28k

ASP .12 can handle more rpm the con rod is made for it.

Mr Cox

Did you correct for Doppler in those numbers?

The ASP .12 seems really feeble in comparison to the Picco which is on a totally different level in terms of quality to the construction etc.

Pond Skipper

Okay flew the Skorch II

APC 5x3 88F light breeze under 6mph
4.1k to 5.2k --idle
25.25k --------in the hand best read peaked to then reduce a bit rich
24.6k to 24.9k set tad rich ready for launch
28.47k -------- best pass 81 mph
27.3k ----------average pass 78 mph
26.54-----------slowest pass 75.4 mph

Run time could have been longer but messed with the engine a bit prior to launch.
4mins and 50 seconds of engine running on 2oz tank a bit rich.
I had tossed it with some up elevator trim, I had to dial out that trim right
away it was looping.
The full length ailerons ended up with 1 click to the right.
Do to the lead I had to add 5 clicks down with half of it gone now I should be able to remove the 5 clicks.

Not bad for the 5x3 speed was exactly where I predicted it to be unloaded thrust was great!
Some pics from start up to flying to landing. The wing area makes it a kitty cat to land.
The full length ailerons made low rates seem touchy. The amount of lift the wing creates
at 2deg incidence allowed me to remove half the tail weight originally installed - now down
to one 6g square piece of lead. Pics taken from the vid. I didn't get to try the 4.75x4 I was
putting the prop on for the second flight and over tighten stripping 4 of the prop nuts aluminum threads.
I have two other prop nuts here on the work bench and will just have to be careful next time.

Pond Skipper

I use a phone app Kris it has been checked with other known verified data and is within the same range (+/- 600 rpm) good enough for me.

Soon I will test this GPS speed logger

combatpigg

My Feedback: (3)

Nice...!
Judging from the numbers you got treated to a pretty nice Audio / Visual Show today..!
With the 70 - 80 mph and concentrated smoke trail you could fly some Big Boy Pattern type stuff.

Pond Skipper

The neon colors really pop in the air I am uploading the vid now

The wing span is bold creating mucho lift for the over all weight. I might be able to get away with a 4.5x4 do to all that lift. Would be fun to scream along at 30k.The 4.75x4 increased load makes it about 900 rpm less than the 5x3 during my static tests however I expect the 4.5x4 to be less load than the 5x3 do to the narrow blades and smaller hub. All the same will test the 4.75 first as planed. I expect with a peaked needle 28k ish about 108 mph. May try the 4.5x4 right off at 30k /114 mph.

combatpigg

My Feedback: (3)

What is amazing is to think that APC is more "On Top" of what we might need to use, than what any of us are.
They don't make any props that don't have a pretty strong application / demand.

Pond Skipper

Ok sorry for the delay YouTube was being slow test vid is 30fps / up to HD starting at 144P thru 1080P


https://www.youtube.com/watch?v=h47Vosb0JFE

https://www.youtube.com/watch?v=h47Vosb0JFE Published on Oct 4, 2015

combatpigg

My Feedback: (3)

The engine sounds like it is right at home. That's good to know that the Vertigo is a good alternative...especially at garage sales and swap meets where car stuff shows up.
So, turn the intensity down on those ailerons and have fun with those 4 pitch props..!

Pond Skipper

Yea the full span ailerons should have a blistering roll rate once I ring this one out. I had it at 65% took it down to 50% tonight should do the trick. I have never had much use for a 3in pitch props on RC planes till today. It was still nice and quite with the Profi pipe perfect for around others. Next vid I will go with full 60fps do to the speed increase it will need it to grab good focus on the subject. I sure wish I had auto zoom lol. I will add 10% zoom next time will help a bit. The Vertigo is worth trying Chuck it can handle another 6k easy. I heard it screaming with a RC car readings to 38k on the straights. The pipe is set to do its best between 33- 34k With that being said I should use the 4.2x4 / 130mph muah hahahah

Yes bought three of them average price 12 dollars ea. thats with shipping to the front door. A hobby store in MI had a lot of three one used two with no signs of use. Only a few bidders to contend with.