radfordc

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I'm using a simpler solution for redundant battery packs. Two LiFe 6.6v packs, two switches, and two diodes installed in the switch harness wires. Either battery or switch can fail and the radio still gets full power. Before each flight check each switch and battery separately to ensure that they are working. I recently had a switch fail in flight on my big 55cc P-40 and caught it on the ground after the flight.

ThunderBoat42

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Been working on the power set up... It blows me away that there is no room for any type of isolation foam padding around the tank. So, making room. The spinner needs to be cut for the 4 blade prop to fit properly. So took an ole jigsaw and mounted it to my old trusty bandsaw cart inverted to do the cutting. Final triningand balancing with a Dremel.

Always like the Corsair too. This is an awesome picture. She is going to be the custom nose art I have been looking for.

ThunderBoat42

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Here is a DEAL

j301

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I cant find the corsair! Looks good, how long before the runup? I dont recall, did you say the 4 blade was for show or functional?

ThunderBoat42

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Something to feat your eyes on for the next P51 Project.   They are about 45 min away... a visit is in order.

ThunderBoat42

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Yeah... What corsair? LOL

Set up for break in tomorrow after work for the YS and the Saito 65 that just got a rebuild. (BTW the other engines in the photo were nasty with years fo castor buildup. Tried some old cheap brake fluid I have been looking at for years that will never be used .. shined them rite up. wow... that was too easy!)

After a few tanks of fuel will mount the 4 blade and take some rpm readings. I have no way of testing the thrust. Been on the to-do list for years... but..... After talking to some YS buddies... I am feeling positive this engine will turn the 4 blade well

Mustang Fever

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ThunderBoat:

I've found this to be pretty accurate:

http://personal.osi.hu/fuzesisz/strc_eng/index.htm

raptureboy

You can test thrust also by mounting it in your plane and then attach a fish scale to the tail and tie it off to a stake or other secure anchor pointand then throttle up. Not the most accurate but close enough.

ThunderBoat42

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WOW!... that is a handy tool! Based on that and the required power... I am good and confirms what some of the YSguys forecast. Of course real world will tell it all. The calculated thrust is more than 1 to 1 ... another plus. The estimated speed is 63mph...thats scale at 1/7th (??) of 434mph. Not the fastest bird.. but the other goodies should compensate in cool factor.
True that Rapture.... good enough and a lot easier that building a dedicated test stand. looking forward to getting home and starting break in. My neighbors are learing to love me *laughing* ... hey, it's not as loud at the motorcross bikes!!

raptureboy

I live on 8 acres so sound is not a problem with the neighbors, but is for my wife There is something I don't understand about the calculator and that is it does not take into account the weight of the plane. Would'nt a 12lb plane be slower than a 10lb plane? Maybe I am missing something. My retracts are suppose to deliver today finally and I have most of the other small details worked out, so I hope to be ready to maiden by next week. over in the battery/charger forum is a thread on A123 cells and where to buy them from, couple of good sources to check out.

Mustang Fever

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Rapture:

The static thrust relates to how well the airplane will accelerate, and how strong it will be with the nose vertical. You have to supply the weight and compare it to the predicted thrust. A 10 pound plane with 5 pounds of thrust will perform OK, but will be nothing to write home about, and will struggle to accelerate for takeoff from a tall grass field. A 10 pound plane with 10 pounds of thrust will be an excellent performer. A 10 pound plane with 15 pounds of thrust will accelerate like a dragster, take off in a very short distance, can be hand launched under all conditions, and will climb vertically til it's out of sight.

Thrust and airspeed are always a trade off when we use fixed pitch props. That's where the calculator really shines. Most guys tend to over or under prop their airplanes. The calculator allows you to play around with different engine and prop sizes until you come up with a combination that gives you a usable airspeed and thrust.

There's another one for electrics that I've had great success with:

http://www.ecalc.ch/motorcalc.htm

raptureboy

Thanks Mustang, I figured I was missing something besides my hairso if I had 15 lbs of thrust and my plane weighed 15lbs then I would have a 1:1 ratio? That would explain why my 10 lb P-40 with the dle 20 and a 15x8 3 blade turning 8700rpm goes like a rocket

ThunderBoat42

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The other one to watch on that calculator is the HP required.  HP is a subject in its self but this provides a good indication it appears.   I didnt assume I would actually see the published HP for the engine.   Being conservative I guess. 

RE Batteries:   I heard in the Charger/Battery section so may good things about the LiFe I went that route.  I may use the LiFe in the Nextar play plane and go with the A123's for this expensive one.  

ThunderBoat42

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Well... break in began with an interesting start. Starter would turn the engine over (its a 24 yr old hobbico standard starter).. hand proped like I do all my YS engines (flip 5 times, add heat and crack throttle, grab spinner and flip backwards - will kick back and start).
Anything over 3500 rpm with it rich... it would lean out and quit but did get a slobbering rich tank though it at 3000rpm and slept on it. This am checked the filter, sure enough, it was sucking air with the fuel at higher rpm. poor sealing filter.
With new filter getting woking properly getting just over 7000rpm slobbering rich... smoked the hood and the smoke getting back in the basement set off the smoke alarms. THAT got the kids up and thefire dept rolling.*laughing*. oops.
Idle is 1900 without heat and 1800 with heat. Another 3 or 4 tanks with the last 2 for tuning and 4 blade prop test ... then ready to install.

the spinner cone is twisting into the prop also.... have to readjust everyr un to get it off the prop. Spninner on prop = disaster. so need to come up with a solution there so I dont ruin a $100 prop.

Bench data reading into the calculator are (and this plane weighs???) BUT re HP values...the optimal prop calculator to calculate the HP/back to given prop/rpm says 3.1. I tent to believe the 3.1hp based on actual reading. either way and HP aside ...the static thrust to prop/rpm are as they are. YS engines are a BEAST at full throttle... with excellent idle.. love them.

Static thrust =	433oz[/b]
273Static thrust=	27.2pound
Static thrust=	12.3kg
Perimeter speed=	167.48m/s
Required engine power=	4.89[/b]HP

ThunderBoat42

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4 blade prop test.... after a gallon of fuel for run in and tuning
Better RMP (slightly) and flywheel action brought the idle way down reliably with no heat.
its a GO on the 4 blade.

j301

My Feedback: (12)

[quote]ORIGINAL: ThunderBoat42



the spinner cone is twisting into the prop also.... have to readjust everyr un to get it off the prop. Spninner on prop = disaster. so need to come up with a solution there so I dont ruin a $100 prop.

Thats looking good! For $100 a prop, think I would foam-peanut the runway!

ThunderBoat42

My Feedback: (1)

They now have a 15x9 prop for the Saito/OS 1.20 and a 16x8 for the YS 120 in scale 4 blade. These things are awesome.....http://www.smigla.com/english/four-blade.html

Mustang Fever

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Here's what I did with mine, after much unfruitful fiddling with the upside down 95AX. It would never run reliably, even tho two of it's little sisters (75AX) did just fine inverted.

Going from the Macs muffler (inverted) to a Slimline pitts (sideways) improved the top RPM. Ran a whole tank through it after adjustments and it never missed a beat, including 3 minutes of idling and then going to wide open. (No hesitation, no stumbling, just blasted off.)

The engine mount and firewall blind nuts are symmetrical enough that this was pretty easy. I did put a couple washers under the top of the mount to get back the required downthrust (and to make the spinner line up with the cowl). Put a couple under the front of the engine to get it to line up from the other perspective.

Hope to fly it Saturday to check everything out.

I really hope it does OK. I've had this bird for going on three years, and have not had any serious fun with it, due to constant problems with the landing gear, the elevator linkage, and the engine.
I've made up my mind if I don't have some fun with it this summer, it's going on the block and I'll get another warbird to replace it.

j301

My Feedback: (12)

Sorry to hear about all the issues, and its good the side mount is working out. Looks like you did a good job of it too, the only bummer is that the quest for making it run right lead to having the lines of the nose interrupted by head and muffler. I completely understand how you got there though, 3 years is a lot of patience!
By the way, I'll take a shot of that apple juice and a couple of them fancy fruit smiles...

Mustang Fever

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I'll ask the wife, but I think she's gonna say "no", get your own.

KaP2011

My Feedback: (17)

Good to see that you've got it worked out. It is a great plane to fly. It flys very much like a sport plane. The 95AX ought to give it some awsome power. Mine flys very well on an OS 91FS.

Good luck Saturday.

Mustang Fever

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Kap: the few times I was able to fly it with the 95 (and the 95 ran sorta good), it seemed like it had an unlimited vertical, and was doing an honest scale 525mph (75 actual).

ton2di

My Feedback: (182)

Wow. What size 4 blade prop is that? Idle looks great. Is that the actual 4 blade rpm (11K+)?

Tony

ThunderBoat42

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Glad to see some birds in the air.   I've had to take a break with business being crazy busy (good thing).  

ThunderBoat42

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KaP -  GREAT pics!!!!