mick15

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Jaketab

My Feedback: (2)

Powerfuel 380 voltage question please.

I have the earlier model 380 and plan to switch the pump through the ignition cut-off. I’m using a 7.4v 5200 mAh Li-Ion battery to power both the ignition and the pump. Engine is the Moki 250. Two options exist to power the pump.

A) Use a “Y� after the fiber optic receiver and power the pump with the full voltage of the battery. Max voltage will be 8.4v at full charge down to 7.2v.

B) Regulate both the pump and the ignition at 5.3v. The regulator is adjustable from 5.2v – 6.5v and has duel leads.

Question – will these options present either too much or too little voltage to operate the pump? Suggestions and help please.

Thanks - Jaketab

vfrank59

I use 2 Optic kill switches. Y-cable from the radio receiver. The two optic kill switches work off the same radio channel. I run a 7.4 battery to the fuel pump and 4 cell battery to the ignition. No regulators needed and each get the correct voltage. They both shut off with the flick of the radio kill switch. works great.

germrb

My Feedback: (3)

Jaketab,

I run off of a SmartFly bus, so that the receiver is isolated. My arrangement is your Option B. That way the ignition and fuel pump voltages are constant. I prefer this arrangement so that if the fuel pump should stall or bind up, the receiver voltage is unaffected. If the pump stalls, the current goes max and you run the risk of pulling down the receiver voltage, to say nothing about your plane. The same logic holds for big digital servos.

Scott Prossen

I do option B on all my planes. 4 years and 7 engines that way with zero troubles. Works for me.

Scott

Jaketab

My Feedback: (2)

Thanks for replies on Powerfuel 380 volt question. My preference is option B - sharing one 5200 mah battery between pump and ignition.
To clarify - I'm using EQ-6 Turbo with opti kill. Battery is connected to charge switch. Charge switch lead to optic cutoff receiver. Optic receiver output to Smartfly adjustable regulator with dual output set at 5.3v. One lead from regulator to ignition and the other lead to pump.

The pump will be OK at around 5.3v to 5.5v ??????
Assuming that the Moki ignition should not see more than 5.5v.

Thank you - Jaketab

P.S. Wish I could make it to Monster Planes. Maybe next year first time with Moki powered Gee Bee R3.

Jaketab

My Feedback: (2)

Although it's not a Warbird, It does have a MOki. Below are some recent pics of the Airworld Gee Bee R3 I am building.
The dreaded sanding and preping for paint starts next. It's been quite a learning experience.

Thanks again - Jaketab

Scott Prossen

Just for clarification, I run my voltage down to 5.1 to 5.3 Seems the pump and ignition like that range in the planes I fly. The Gee Bee looks awesome. Is that a 250 or 400?

Scott

kipuetz

Dear Friends,
I
have just received my Moki150 engine.I must say,it is just beautiful! It will go into my 1/4 Focke Wulf. I mounted it onto a test stand and started it for the first time,with 27-10 Prop.I ran it for about 10 minutes various revs.I am completely happy so far,it sounds like a small Hearley, does it not?
Next I put a 26-14three blade prop on it and thougt, I try to retune to suit .I am stuck big time now.I have totally lost the initial carburetor settings.The engine will easilystart with 1 -1/2 low end 1 1/4 high end .Now,I am no mechanic,neither am I total beginner!
Can anybody help?What are the steps to bring the engine past the midrange of 2500 RPM to full throttle of 4600 RPM with this three blade prop.!
Regards,Karl in Australia.

mick15

transpose your two needle values, should be about right. mine is turning a 32x14 3blade quite happily.

m

FormerCA.

My Feedback: (8)

That's nice! What did you use for exhaust?

Scott Prossen

You should know that Mick is referring to how his 250 turns a 32x14 not his 150.

Scott

Jaketab

My Feedback: (2)

It's a 250 on the GB-R3. The exhaust is 6061 aluminum from McMaster-Carr. Cost of 3' was $11.00 including shipping. Sure beats paying as much has $130 for a custom exhaust. Outside dia is .875. Inside is .805". Wall thickness is .035. Used a pipe bender with 7/8 wheel. This was my first attempt at tube bending. Got it right the first time.
Trick is to fill and plug the tube with sand or salt to keep from crimping. Go slowly. McMaster has almost any size you need. Link below.
Have not run yet with the exhaust so I don't know what sound note will be. The tubes are 16" - but are smooth wall so should help exhaust flow.

http://www.mcmaster.com/#tubing/=egi55z

Jaketab

FormerCA.

My Feedback: (8)

Thanks Jake

I know you can use copper tubing as listed in the P47 thunderbolt instructions but I liked your install better.

FormerCA.

My Feedback: (8)

Just got off of the phone with Mcmaster-Car, ordered 2 36 inch pieces of tubing. Very friendly service.

FormerCA.

My Feedback: (8)

Jake

Is the GeeBee gonna have smoke? If so, where are you gonna tap in at?

germrb

My Feedback: (3)

Scott,

I was struck by Mick's comment about transposing the needle valve setting. I have been collecting needle valve settings from people who have been kind enough to provide them. After Mick's comment, I went back through my data and recognized that all of the Moki engine valve settings have the high speed valve settings larger than the low speed setting. On twins and single cylinder engines it is usually the opposite. Typical settings on twins/singles are H=1+/- and L= 1 3/4+/-. Since you have more Moki engines than everyone I know, do you find this to be true? Do you have any settings data for 150s or 250s?

I've been chasing heat problems, without a lot of success, and found that almost all my engine data has had the low valves set higher than the high speed valves. I'm begining to think that I'm in the wrong ballpark. Any thoughts?

mick15

Whilst I believe the setting I have given are realistic you need to bear in mind I have a fuel pump which is adjustable from the transmitter, the overall pump speed is trimmed from a rotary control the pump speed is mixed to the throttle channel. Therefore you will realise I have total control over the mixture at all times.

m

germrb

My Feedback: (3)

Mick,

I also run a fuel pump, although it is not contolled by the throttle. What I am wondering is if the carb settings for radial engines is inherently different then for single or twin cylinder 2 cyle engines. Everyone, except me, seems to have the high speed valve set higher than the low speed valve. Since I can't seem to get my 250 #1 cylinder lower than about 115C in flight, I am begining to suspect that my valve settings are not correct even though the engine seems to run very smoothly.

The attachment shows the temperature profile of my 250 for three flights along with the valve settings. The top profile is cylinder #1 and the lower is cylinder #3. Obviously, the goal is to get #1 lower and #3 higher. BTW I'm flying at 4300'

Jaketab

My Feedback: (2)

FormerCA

Yes the Gee Bee R3 will have 32oz smoke. Slimline smoke pump plugs into chan 9 directly on the JR 921 Receiver. Running separate battery (7.4v) which plugs directly to pump.
The collector ring (on top behind #1 cylinder) is already tapped for 5mm or 10-32. However, a 10-32 smoke nipple is a little loose in the 5mm hole.

Gentlemen,

Regarding valve lash settings, I've got conflicting info from 2 sources. One may have been a typo.
Is the correct valve gap .005 - .008 (thousands) ?????? Is this for both intake and exhaust ???????

Thanks - Jaketab

wxman2

My Feedback: (52)

Jaketab,

I have about another week or so before Igo pick up a Moki 250 and LA-7 from Teamaeroscale. Does the outside .875. Inside .805" with .a wall thickness is .035 tubing slide over the Moki 250 exhaust ports or are you using teflon to join them? I just trying to have everything on hand to build a custom exhaust for the LA-7.

Thanks,
John

germrb

My Feedback: (3)

John,

The exhaust ports are 20mm (0.787"), so it will not be a perfect fit. You'll have to cut a couple of slits in the tubing and use a hose clamp. I use Permatex "Ultra Copper" gasket material to seal the joint. The material makes great gaskets for mufflers and will tolerate the high temperatures.

Jaketab

My Feedback: (2)

John,

Did exactly as Bob said. The tubing slides over the exhaust outlet. No teflon - just coat with Permatex.
My 250 outlets also measured about .787."
The next size down inside wall is .777" which is too small to fit over the exhaust outlets.
If you groove the tubing (.875/.805) it will snug down with hose clamps.
If your exhaust tubes are on the long side then probabally need supported by bracket.
The pipe bender I used was for 7/8" pipe with a large radius die. I would not try to bend it less than a 6" radius or risk crimping.

Can anyone comment on the valve gaps ??? Is .006 to .008 correct ????

Jaketab

Jaketab

My Feedback: (2)

Type General Purpose Aluminum Tubing
Metal Aluminum
Aluminum Material Alloy 6061
Material Aluminum Alloy 6061
Shape Single Line
System of Measurement Inch
Outside Dia. 7/8" (.875")
Inside Dia. .805"
Wall Thickness .035"
Maximum Pressure Range, psi 501-750
Maximum Pressure 749 psi @ 72º F
Low Temperature Range -499° to -400° F
High Temperature Range +301° to +500° F
Operating Temperature Range -452° to +400° F
Metal Bendability Bendable With Bending Tool
Temper Hard T6
Metal Construction Seamless
For Use With Air and Fuel and Hydraulic Fluid and Water
Fittings Used Compression
Specifications Met Aerospace Material Specifications (AMS) and American Society for Testing and Materials (ASTM)
ASTM Specification ASTM B210
AMS Specification AMS-WW-T-700/6

FormerCA.

My Feedback: (8)

That's the tubing that I ordered.