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.049 on a Spirit

Old 06-28-2004, 04:14 PM
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ptarp
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Default .049 on a Spirit

I'm putting a Cox .049 engine on the nose of my GP Spirit. Should I give it any upthrust, downthrust, or make it neutral?

I got tired very soon of messing with a high-start system, so I thought I'd slap a .049 from a CL plane I had sitting around for years. I had 1.75oz in the nose to balance it before, and it just so happens, that is the exact weight of the .049 (however, it is more forward than the weights were). So, except for the drag of the engine and prop, it should work out pretty well.
Old 06-28-2004, 05:32 PM
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SST
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Default RE: .049 on a Spirit

I motorize all my sailplanes, but a Cox reed motor will need all the help you can give it to lift a 2-meter sailplane, though it will do it. Try a 5X3 2-blade cox prop (a gray if you can find one) and 25% or more all castor fuel. Yes, you'll need downthrust, I'd start with about 3* and go from there. If you climb under power when you're trimmed for level glide, add more. I usually add just enough right thrust to see it, as this doesn't seem to be very necessary, since given the long lever moment to the tail of most sailplanes, the tail seems able to overcome the tendency of the motor to turn it.
Old 06-28-2004, 06:54 PM
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Default RE: .049 on a Spirit

I had a gentle lady with a tee-dee .049 power pod. I ran the tee-dee with crank pressure to the tank and a fairly hot fuel. I believe the prop was a 5 1/4 x 4. This was barely sufficient to get the plane in the air. If I had to do it again I'd use a .09
Old 06-28-2004, 07:42 PM
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Default RE: .049 on a Spirit

It all depends on the weight of the model. I've seen GL's with TeeDees climb like homesick angels and I've seen some that barely glide uphill. How much does your Spirit weigh right now?

If that control line model engine is the one with no tank on it then it's probably the hotter 290 with the twin bypass flutes in the cylinder. If so then it's a pretty hot little engine.

You may also want to try an APC 6x2. I had great luck with that one on an overweight free flight model one time. For slow climbing it was better than the 5x3 grey Cox prop.
Old 06-28-2004, 09:38 PM
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ptarp
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Default RE: .049 on a Spirit

Yes, it uses an external fuel tank which I am going to mount under the canopy in one of the empty bays. I mounted the engine and started it, and with a 6x3 prop, it seems to have amazing pull for such a tiny engine. I'm using the cox %15 nitro fuel right now. I have some hobbico %25 ordered, so it will boost it a bit more. I'm hoping to try it tomorrow, so I'll let you know how it goes.

I'm not sure of the weight of the spirit. I have used all micro electronics and I even took the spring starter off the motor to save a bit of weight. I used a heat gun to pre-heat the cylinder, and it started 3rd flip
Old 06-28-2004, 10:13 PM
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Default RE: .049 on a Spirit

I had a black widow .049 on a glider just slightly smaller than the Spirit. It went like a bullet. Too fast to control. If the .049 doesn't get the Spirit up to altitude, with fuel to spare, then please let me know so I can go out and buy some spices, as I will sprinkle them on my shirt before I eat it.

Vic
P.S. Let me know how it went.
Old 06-28-2004, 10:39 PM
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ptarp
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Default RE: .049 on a Spirit

ROFL!!!
Funny stuff

Can you get that thing to torque roll with that .049?

What is the major difference between Cox's line of .049 engines?
Old 06-28-2004, 10:50 PM
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Tall Paul
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Default RE: .049 on a Spirit

I have a GL with an OS 15FP. Gets to speck altitude in less than a minute.
Old 06-29-2004, 01:56 AM
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Default RE: .049 on a Spirit

ORIGINAL: Tall Paul

I have a GL with an OS 15FP. Gets to speck altitude in less than a minute.
[X(] Let me guess Paul. Secretly you're a frustrated free flight FAI power flyer at heart...

Ptarp, the engine you have is basically the same as that Black Widow but without the rear tank or the black finish. In the final days of Cox the engine you have was sold with a couple of small improvements as the Killer Bee and was considered to be the hottest reedie mill they made.

Watch how far back you put the fuel tank. Remember that if you set up a nice climb angle the engine will have to pull the fuel uphill and if it's too far back it'll run unevenly and may quit before the fuel is gone. It's best to keep the tank as close to the carb as is possible even if that means putting the batteries further back just behind the tank.

Do a search in the 1/2A forum area for "Fuji film tank" for a good thread on making a nice tank from the Fuji 35mm film storage cases.

With that micro gear you're probably in the sweet part of the weight ballpark. It sounds like you'll be fine and happy.
Old 06-29-2004, 11:09 AM
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ptarp
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Default RE: .049 on a Spirit

Right now the fuel tank is about 2" behind the motor, in the closest bay. Do you think that is too far?
Old 06-29-2004, 03:26 PM
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Default RE: .049 on a Spirit

That's certianly pushing the limits but it'll work if you tune the engine with the model held about 10 degrees nose up and do not try to do any aerobatics on the way up. Just a steady climb with circles to keep it in the area. I would not ever set up an aerobatic or even standard sport flying model with it that far back. But for a powered glider where the engine is only to replace the launch equipment it may work OK.

If it conks out too often or you intend to sport fly during the powered portion before climbing for height then it'll have to swap places with the battery pack, which I assume in located in the first bay between the engine and the tank.
Old 06-29-2004, 08:13 PM
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ptarp
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Default RE: .049 on a Spirit

Well, I tried it and it worked fine. That engine gives just enough oomph to get it up as high as my high-start did with about 1/10 the hassle. I'm very happy I put it on. It wasn't a very good day for thermals(plus, I'm not skilled at finding them), so the flights weren't very long. I didn't have a steep climb angle (even if I wanted to), so the engine didn't have any trouble drawing the fuel. Thanks for the info guys!
Old 06-29-2004, 10:02 PM
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Tall Paul
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Default RE: .049 on a Spirit

ORIGINAL: BMatthews

ORIGINAL: Tall Paul

I have a GL with an OS 15FP. Gets to speck altitude in less than a minute.
[X(] Let me guess Paul. Secretly you're a frustrated free flight FAI power flyer at heart...
.
Am I that transparent?
I've spent many a day chasing FAI free flights way back when...
I used to dread being close to one when it d-t'd... They'd come down with a real THUMP!!!!
Old 06-30-2004, 01:58 AM
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Default RE: .049 on a Spirit

The big OT sparkies make the earth shake... really. I felt one through my feet that thumped down about 10 feet from me once.

Ptarp, get yourself an APC 6x2, I think you'll find it helps. But either way it sounds like you need to let the model come up to speed and set it's own climb rate. At this sort of power loading it's important to let the wing earn it's keep. A bit of playing with this factor may get you a little higher.

And congrats on a successful modification.
Old 06-30-2004, 12:37 PM
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ptarp
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Default RE: .049 on a Spirit

Interesting Thanks, I'll try that. Also, I noticed that I accidentally put some up thrust on the engine. I guess I need to fix that.
Old 06-30-2004, 10:19 PM
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Default RE: .049 on a Spirit

I had a gentle lady with a tee-dee .049 power pod. I ran the tee-dee with crank pressure to the tank and a fairly hot fuel. I believe the prop was a 5 1/4 x 4. This was barely sufficient to get the plane in the air. If I had to do it again I'd use a .09
Wow - that must have been a heavy GL. I had a GL years ago with a TD .049 and it was fine. I also flew an Olympic II for years with an engine pylon cut from 1/4" light ply to fit as a "rib" between the two wing halfs with the same TD .049 on it, flew great with enough run-time to get fairly high.
Old 07-28-2004, 05:22 PM
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Default RE: .049 on a Spirit

I have a norvel .061 on a power pod on my spirit--what a differance in climb and power compared to the .049.....pulls it up with no problem.......joe
Old 08-27-2004, 09:48 AM
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Default RE: .049 on a Spirit

I run a black widow and venom .049 on my spirit with about 1 degree of down thrust and it pulls the snot out of it. I run an apc 5.7x3 prop, high compression head and either cool power or omega 10% fuel. The venom turns 16,500 fully leaned out and the smaller prop has a little less drag. I also use the extended tanks but I only fill them up on a windy day. Most times, I fill them to about 60-70% of capacity.
Old 09-07-2004, 07:28 PM
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Tim Wiltse-RCU
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Default RE: .049 on a Spirit

Scot,

Are you really running a real VENOM to tow up a glider???? Red crankcase and black tank?????? If so then you win the award for the person that is abusing a Cox engine the most

LAter,
Tim
Old 09-07-2004, 09:04 PM
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Default RE: .049 on a Spirit

You got it. It is the one you are talking of plus a Klaus extended tank. I did some research on it and found out they only made that engine in 1995. Not sure how much more power it has than the Widow, but it is the best running Cox motor I have ever had. Starts in 1 to 2 flips 90% of the time. Not sure what peak rpm is but on the ground it turns 16800. When I put the spirit in a loop, on the downside, it speeds up alot (maybe 2000 more rpm). I should swap it out for the Widow and save this motor for something special.


Scot
Old 09-08-2004, 07:14 AM
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Tim Wiltse-RCU
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Default RE: .049 on a Spirit

Scot,

You should save it or sell it to make your next car payment. Cox only made 1,000 of them. They are the hottest reed valve engine Cox made. In stock form they would turn 20,000 plus. They are a racing engine and lugging it down with a big prop is killing it. Switch that sucker out with a Black Widow. Even a Black Widow can turn a APC 6x3 at 16,500. As long as the Venom still has it's factory cylinder,piston and crank it's worth $100 easy.

Later,
Tim
Old 09-08-2004, 08:28 AM
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rscarawa
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Default RE: .049 on a Spirit

It sounds like I should change it out. I had no idea they were worth that. Why did they stop making them?

Scot
Old 09-08-2004, 11:13 PM
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Default RE: .049 on a Spirit

I had a Black Widow on the nose of a Wanderer. When the engine got tired, I replaced it with a Norvel .061 upstart, which has a gas tank/ mount. The tank is larger than the Cox engine but I usually only fill it half full or so. I use an APC 5.75x3 prop. It is a far better performer than the Black Widow.

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