What would be a good power plant?

oldguy Thu Dec 03, 2020 3:13 pm

I have this plane that needs a power plant. The plane has a 25" ws, is 15" long and weighs 5.1 oz as seen.
What would be a good engine for this. I built it with a medallion 09. , which just doesn't cut it. No power.

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**944_Jim** Thu Dec 03, 2020 4:19 pm

I don't get it...

My Scientific P-40 was 8.5 oz with an AP .061. It hauled the groceries quite well. What concerns me is that your plane is lighter for the same size, yet reportedly didn't do too well with a Medallion .09.

I am concerned that a Medallion .09 can't handle a 1/2A model...I hoped for better. Especially since I planned on two for my 36" Reproduction Frog Mosquito.

Can you bench test and tach it? I'd you don't have a tach, I know RPM Gauge is available for Android devices. It does an auditory check to provide engine speed. There may be an Apple "iThingy" version.

Using information like given prop, engine speed, and fuel content can provide us with details to assist.

NEW222 Thu Dec 03, 2020 6:33 pm

Sorry I cannot be of any real help with the plane, but I would imagine that a Medallion .09 should be able to haul that around fine myself. Something seems a bit off. Anyways, why I am really posting. Nice looking plane. Is it a Ringmaster with a diamond airfoil wing? Looks good.

OhBee Thu Dec 03, 2020 7:23 pm

Ya...i would think an 09 medallion would haul that around nicely! Something is amiss!

oldguy Thu Dec 03, 2020 7:49 pm

944_Jim wrote:I don't get it...

My Scientific P-40 was 8.5 oz with an AP .061. It hauled the groceries quite well. What concerns me is that your plane is lighter for the same size, yet reportedly didn't do too well with a Medallion .09.

I am concerned that a Medallion .09 can't handle a 1/2A model...I hoped for better. Especially since I planned on two for my 36" Reproduction Frog Mosquito.

Can you bench test and tach it? I'd you don't have a tach, I know RPM Gauge is available for Android devices. It does an auditory check to provide engine speed. There may be an Apple "iThingy" version.

Using information like given prop, engine speed, and fuel content can provide us with details to assist.

I built this plane just for the .09 medallion that i pickup. I have never had .09 medallion before but just thought it would work fine. It has no power. Tried 7x3 and 7x4 props on 25% nitro, don't know rpms but it never did wind up like most engines i'm used to. I don't have a tach, and not setup here yet to run it on a stand yet, recently moved to Idaho.

oldguy Thu Dec 03, 2020 7:51 pm

NEW222 wrote:Sorry I cannot be of any real help with the plane, but I would imagine that a Medallion .09 should be able to haul that around fine myself. Something seems a bit off. Anyways, why I am really posting. Nice looking plane. Is it a Ringmaster with a diamond airfoil wing? Looks good.

Yes it's a somewhat ringmaster. It's not a diamond airfoil looks that way in the picture, but not. What i have read on the net that .09 medallion engine surely isn't a power house at all.

**944_Jim** Thu Dec 03, 2020 9:41 pm

oldguy wrote:

I built this plane just for the .09 medallion that i pickup. I have never had .09 medallion before but just thought it would work fine. It has no power. Tried 7x3 and 7x4 props on 25% nitro, don't know rpms but it never did wind up like most engines i'm used to. I don't have a tach, and not setup here yet to run it on a stand yet, recently moved to Idaho.

Do you have an Android tablet or phone? Try the program "RPM Gauge." It installs quickly, and uses the microphone on the device to check by sound. I did, and found it gave very similar results to my engine tach. I think I have one of my .09s on my test stand. I'll try to spin mine up and tach it this weekend, and report results here.

**Cribbs74** Thu Dec 03, 2020 9:43 pm

A Medallion .049 would be sufficient. Something is definitely wrong with your .09.

What’s the engine history? Did you break it down and clean it out? Compression?

Ron

oldguy Thu Dec 03, 2020 10:39 pm

Cribbs74 wrote:A Medallion .049 would be sufficient. Something is definitely wrong with your .09.

What’s the engine history? Did you break it down and clean it out? Compression?

Ron

I did break it down when i got it and cleaned it up. Compression, for cox seems to be about normal.
I was thinking more like a .10 size engine. I don't think a medallion .049 would pull it like i would like.

**944_Jim** Thu Dec 03, 2020 11:07 pm

Oldguy,

Here is a brief review of the Cox engines by displacement and type:
http://sceptreflight.com/Model%20Engine%20Tests/Cox%20Tee%20Dee%20and%20Medallions.html

I noted the article claims a 6x4 prop yields 16k rpm, a 7x3/15.5k roms, 7x4/ 14k rpm.

**Cribbs74** Fri Dec 04, 2020 12:32 am

oldguy wrote:
Cribbs74 wrote:A Medallion .049 would be sufficient. Something is definitely wrong with your .09.

What’s the engine history? Did you break it down and clean it out? Compression?

Ron

I did break it down when i got it and cleaned it up. Compression, for cox seems to be about normal.
I was thinking more like a .10 size engine. I don't think a medallion .049 would pull it like i would like.

Well how fast do you want it to go?

Here is an old video of my PDQ/Brodak Baby Clown. It’s plenty fast and has 25” wingspan and 15” fuse length weighing in at a hefty 8.75oz. Power is a tired TD .049 in the video. currently running a Medallion TD Hybrid (TD with Medallion intake)

The .09 should have considerable more go juice and with the weight and dimensions being less than my Baby Clown it will fly just fine with an .049. Seeing is believing.

dirk gently Fri Dec 04, 2020 3:11 am

oldguy wrote: don't know rpms but it never did wind up like most engines i'm used to. I don't have a tach, and not setup here yet to run it on a stand yet, recently moved to Idaho.

You don't actually need a tach. Just a guitar or a piano Smile

You hear the note the engine is "playing" and google what its frequency is, then multiply by 60 for the rpm.
If you're not the musical type, you can just upload a video of the engine running and I will tell you the rpm.

fredvon4 Fri Dec 04, 2020 9:24 am

hard for me to understand even a poorly running .09 medallion struggling with a 5.1 oz plane

verify the weight please...

tell us fuel mix --nitro and oil

tell us tank and mounting

what lines and length

at that weight a .09 on 25% vitimin N and 40' spider wire, 6x4 to 7x3 should be screwing you into the ground with around 3 to 3.5 second laps

my opinion is a Cox .09 medallion is quite powerful vs its weight

not doubting your observations and experience oldguy

this is one head scratcher suited just for CEF regulars to dig into

I have TeeDee .049s that will haul 5.1 oz easily but on 30 35 foot lines and 35% N

oldguy Fri Dec 04, 2020 11:47 am

fredvon4 wrote:hard for me to understand even a poorly running .09 medallion struggling with a 5.1 oz plane

verify the weight please...

tell us fuel mix --nitro and oil

tell us tank and mounting

what lines and length

at that weight a .09 on 25% vitimin N and 40' spider wire, 6x4 to 7x3 should be screwing you into the ground with around 3 to 3.5 second laps

my opinion is a Cox .09 medallion is quite powerful vs its weight

not doubting your observations and experience oldguy

this is one head scratcher suited just for CEF regulars to dig into

I have TeeDee .049s that will haul 5.1 oz easily but on 30 35 foot lines and 35% N

What i have read about the .o9 medallion is it isn't any kind of power house.

looks like the 09 Medallion is not exactly an rpm monster, the manual states as follows:

6D x 4P - 15000rpm (smallest prop)
8D X 4P - 10800rpm (biggest prop)

Maybe i need to try a 6x4 or 3 prop on it because it just doesn't wind up. Huh...

oldguy Fri Dec 04, 2020 11:51 am

Cribbs74 wrote:
oldguy wrote:
Cribbs74 wrote:A Medallion .049 would be sufficient. Something is definitely wrong with your .09.

What’s the engine history? Did you break it down and clean it out? Compression?

Ron

I did break it down when i got it and cleaned it up. Compression, for cox seems to be about normal.
I was thinking more like a .10 size engine. I don't think a medallion .049 would pull it like i would like.

Well how fast do you want it to go?

Here is an old video of my PDQ/Brodak Baby Clown. It’s plenty fast and has 25” wingspan and 15” fuse length weighing in at a hefty 8.75oz. Power is a tired TD .049 in the video. currently running a Medallion TD Hybrid (TD with Medallion intake)

The .09 should have considerable more go juice and with the weight and dimensions being less than my Baby Clown it will fly just fine with an .049. Seeing is believing.

Looks like your flying on 25 or 30ft lines, and your using A TD .049, for power, which is a totally different performing engine.

oldguy Fri Dec 04, 2020 12:02 pm

fredvon4 wrote:hard for me to understand even a poorly running .09 medallion struggling with a 5.1 oz plane

verify the weight please...

tell us fuel mix --nitro and oil

tell us tank and mounting

what lines and length

at that weight a .09 on 25% vitimin N and 40' spider wire, 6x4 to 7x3 should be screwing you into the ground with around 3 to 3.5 second laps

my opinion is a Cox .09 medallion is quite powerful vs its weight

not doubting your observations and experience oldguy

this is one head scratcher suited just for CEF regulars to dig into

I have TeeDee .049s that will haul 5.1 oz. easily but on 30 35 foot lines and 35% N

Not trying to start anything here, just posting what i have observed. Didn't mean to ruffle any cox feathers.

**944_Jim** Fri Dec 04, 2020 12:10 pm

And also report how many head gaskets. I'm wondering if this engine is over-conpressed.

fredvon4 Fri Dec 04, 2020 1:13 pm

oldguy wrote:
fredvon4 wrote:hard for me to understand even a poorly running .09 medallion struggling with a 5.1 oz plane

verify the weight please...

tell us fuel mix --nitro and oil

tell us tank and mounting

what lines and length

at that weight a .09 on 25% vitimin N and 40' spider wire, 6x4 to 7x3 should be screwing you into the ground with around 3 to 3.5 second laps

my opinion is a Cox .09 medallion is quite powerful vs its weight

not doubting your observations and experience oldguy

this is one head scratcher suited just for CEF regulars to dig into

I have TeeDee .049s that will haul 5.1 oz. easily but on 30 35 foot lines and 35% N

Not trying to start anything here, just posting what i have observed. Didn't mean to ruffle any cox feathers.

MY feathers are certainly not ruffled but sounds like I ruffled yours

.09 Medallions are not under powered ... Point Ron was making and I tried to point out---- a .049 TeeDee can haul that freight -----so we both are baffled that a .09 Medallion can't

oldguy Fri Dec 04, 2020 2:17 pm

fredvon4 wrote:
oldguy wrote:
fredvon4 wrote:hard for me to understand even a poorly running .09 medallion struggling with a 5.1 oz plane

verify the weight please...

tell us fuel mix --nitro and oil

tell us tank and mounting

what lines and length

at that weight a .09 on 25% vitimin N and 40' spider wire, 6x4 to 7x3 should be screwing you into the ground with around 3 to 3.5 second laps

my opinion is a Cox .09 medallion is quite powerful vs its weight

not doubting your observations and experience oldguy

this is one head scratcher suited just for CEF regulars to dig into

I have TeeDee .049s that will haul 5.1 oz. easily but on 30 35 foot lines and 35% N

Not trying to start anything here, just posting what i have observed. Didn't mean to ruffle any cox feathers.

MY feathers are certainly not ruffled but sounds like I ruffled yours

.09 Medallions are not under powered ... Point Ron was making and I tried to point out---- a .049 TeeDee can haul that freight -----so we both are baffled that a .09 Medallion can't

No sir my feathers not ruffled at all as i said i was just posting my obseration of what i had experienced with this .09.

oldguy Fri Dec 04, 2020 2:22 pm

944_Jim wrote:And also report how many head gaskets. I'm wondering if this engine is over-conpressed.

This .09 has 1 copper head gasket installed. with a new glow plug. Sig fuel 25% Nitromethane
20% Lubricating Oils
(1/2 Castor, 1/2 Klotz).

So with the response i have been given here, i will have to put more effort into this .09 and see if i can get this engine to perform. Would tapping pressure off the side of the case with the nipple improve things. i would not want to have to replace the nva assembly to do this.

**944_Jim** Fri Dec 04, 2020 4:57 pm

OG,

It's a Medallion. No pressure needed for a test run. I'll have mine up and running tomorrow day and will record the run.
It will be measured fuel load, prop size (or two), tached and timed.
Then you can look to see what yours does for comparison.

It would be good to bench mount yours just so you don't have to come up with a way to hold the plane. I do suggest using an Android phone/tablet or tach to get good numbers.

My only concern is my fuel...I think I have some mixed with low Nitro for my Fox .35. I may have some higher Nitro available.

When you had it apart, did you check for excessive ball/socket play between the piston and conrod? How about between conrod and crank? And it may be worth doing a quick leak-down test to see it the crank is leaking out the front of the block, and for m.piston to block. I like to use alcohol for a "wet leak-down test." Cheesy? Yup...but it does give us more information.

Ken Cook Fri Dec 04, 2020 5:04 pm

I'm coming into this topic quite late and didn't have the time to read all of the responses. I for one wouldn't tap the .09 for pressure as it's not needed anyhow and it causes many issues. For starters, the engine will flood very easy the second you turn the prop and the other is timed crank pressure has a positive and negative impact on the tank without using a one way valve. Generally speaking, a stock needle is all that's needed for using back plate or timed pressure running. The only time you really require finer threads is when using a bladder and there's no offerings for the .09 without making something . A TD .09 plug would offer a touch more but the crank timing is mild therefore your only going to see so much of a improvement.

If you've might have read the Whipsaw thread, I mentioned one thing that would make the Whipsaw fly like a turd and that was using a large engine such as a .19 which was recommended on the box. I also said that the Whipsaw is quite small, larger than a 1/2A but smaller than a .15 but a Tee Dee .09 would be a perfect match. I also said that on the Super Whipsaw I was using a .15 size engine which a .35 was recommended.

The problem could be that the engine is too heavy for the small wingspan and that your plane is doing all it can just too sustain the heavier weight up front. After all, a Medallion .09 is nearing 2X's the weight of a Medallion .049 I've seen this when a club member used a Fox .35 on the front of a Jr Ringmaster. It didn't fly a gazillion miles an hour, it flew like crap and went no faster than having a .15 up front.

oldguy Fri Dec 04, 2020 6:04 pm

QOUTE: The problem could be that the engine is too heavy for the small wingspan and that your plane is doing all it can just too sustain the heavier weight up front. After all, a Medallion .09 is nearing 2X's the weight of a Medallion .049 I've seen this when a club member used a Fox .35 on the front of a Jr Ringmaster. It didn't fly a gazillion miles an hour, it flew like crap and went no faster than having a .15 up front.

This could have something to do with it.

**Cribbs74** Fri Dec 04, 2020 6:21 pm

Ok, just for grins here is an old video when I first started out with CL before I changed the fuse to PDQ using the Brodak wing. 25 1/4” Span 15” fuse length and if I recall correctly roughy 8oz. 32ft lines which is all I could get away with at that time in my yard. Engine....wait for it.....Medallion .049 25% nitro Sig.

You mentioned my line length being 25-30ft in your earlier post. What line length are you using?

Ron

oldguy Fri Dec 04, 2020 10:35 pm

Cribbs74 wrote:Ok, just for grins here is an old video when I first started out with CL before I changed the fuse to PDQ using the Brodak wing. 25 1/4” Span 15” fuse length and if I recall correctly roughy 8oz. 32ft lines which is all I could get away with at that time in my yard. Engine....wait for it.....Medallion .049 25% nitro Sig.

You mentioned my line length being 25-30ft in your earlier post. What line length are you using?

Ron

Very nice flying baby clown. All my 1/2A's are running .049. golden bees.
The plane in question was flown with 42' lines.

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