This post is really for someone who has flown ModelTech's Me-109 ARF and knows what this model can and cannot do in the air.
I recently have came across one of ModelTech's Me109 warbirds. This is my first nitro but not a first warbird. I haver mostlyflown park flyer warbirds. I know this is a fast warbird, and that the minium displacement raiting is around .25. Bottom line is that I really want to go nice and slow that will alow me for quicker responce time and allow me to get used to a nitro warbird. Can I get away with using a smaller displacement than a .25 say a OS .15? or will this not be enough power for this airplane. Prop is 9X6.


pLanE NuTs,
Drypipe

For those of us not specifically familiar with that exact model, perhaps you can give us some of the specs such as wing area and All Up Weight (AUW ) without the engine. I have flown the OS .15s and the Magnum .15s and have a good feel for their performance for 2.5-3lb planes with 550-600in2 area. Prop size will need to be determined for the engine you choose, not the other way around, IMO.

BNC

Ya know that left stick on you TX that controls the throttle? It's variable! You dont have to fly balls to the wall all the time.

But seriously. If the .25FX intimidates you, look for a good used .25 FP or .25 LA. The plane bearing engines have just a little less power and wouldstill make the planeflyable. You will find that you will always be flying full throttle though. This is not a typical 1/12 scale combat bird. Its closer to 1/9. Modeltech classifies it as a .25-.36 bird. Put an OS .25FX in it and you wont be disappointed.

My $.02

I agree with Buzz, I have a friend who flies one of these with an FX and I doubt a .15 would fly it.

Power is your friend on take off. Given the choice between having an OS 25 FX or something of lesser power I would <u>always choose the 25 fx.

</u>Once in the air throttle back and fly it slowly. If you need the power it is there on demand.

BNC,
ME-109: Wing Span: 45", Wing Area: 360 sq in., Wing Loading: 20.39oz/ft.

OR My LHS said try to use a 10X4 twin blade propor 3 blade prop 10x4-9x7.



pLaNE NuTs,
Drypipe

I have forgot to say that I picked this warbird up used and it does have a GMS .32 engine already installed! May fault. This is the reason I felt like trying out a smaller engine first. I meant to say replace the .32GMS nock offwith an OS.15 OR .25.

My LHS said try a 10x4 prop or a 3 blade prop with a lower pitch.

The guy I purchased the plane from insisted that a higher pitch prop will always fly a little slower than a lower pitched prop??He said that I should start with a 9x6 with theGMS .32 and not with a 9x5? I always thought that a lower pitch prop is like a lower gear and will give you lower top end speed but higer speed on starts? He insisted that a9x5 prop is faster that a 9X6 prop.
A 9X6it will produce more friction ordrag through the air, thus slower speeds but will have more thrust/torque on take offs?


pLaNE NuTs,
Drypipe

You are right, your friend is wrong.

A higher pitched prop will gain more speed on a straight run, but you will lose it on turns. A lower pitched prop wont go as fast but will maintain a better speed in and out of turns, and is much better for hand launching.

I had argued this point with him through email because I purchased the plane through ebay for $85.00. He seemed to be so sure about this theory!

What do you think of using a 3 blade prop to keep the speed down? The Me-109 will look scale too! What size would you recommend?


PlaNe Nuts,
Drypipe

A .15 sized engine would just manage to get it in the air and fly.  The .18 TT is about the smallest engine I would consider.  Or a .30 four stroke which has about the same power as a .20 sized  two stroke.  I think you would be happier with a low performance .25 sized engine.  Or a higer performance engine with half throttle.

Ya, it does help so much to ask questions on this forum. With electrics you get instant throttle responce. I will first tru out the .32 GMSBB engine with a 3 blade prop.

What size and pitch would you guys recommend on a 3 blade set up?</p>

In RCCA 2548 scale combat, the planes are built to a maximum 48 inch span and a minimum weight of 3.25 poinds, and we run an OS25FX with a 10-3 prop at around 14,500 rpm. It pulls like a tractor, but the lower pitch keeps our max airspeed to around 60-65 mph straight and level, but the pull good in turns..just a little fyi..
Cash</p>

OS.25fx with a 10x3. 65mph. I think I could handel this speed. But I don't know until I give it a try.
.Good info! Thank you.
Would a 9X3 produce even less speed?


pLaNe NuTs,
Drypipe

I flew this several times this weekend (buddy's plane). He had a Magnum .28 with a 9x6 prop. It wasn't very well-powered. I convinced him to run an 8x7 and it made a huge difference. MUCH more power on takeoff and lots more speed. As large as the wingspan is, I wouldn't hesitate to put a 32-36 size engine in it. It is very solidly built and turns like a pylon racer. I am planning on getting one soon to add to my Mini-warbird collection.

8x7 is best for the Modeltech Me-109. Faster, more power than a 9x7? Why is that?
I have a .32 GMS engine.


Plane Nuts
drypipe

For smaller, light planes, the smaller diameter/higher pitch props allow the rpms to stay very high. They won't climb as well, but they will scream in the horizontal. My buddies and I have been racing the GP Combat 25s for the past several months and we have learned a lot about wringing every bit of speed out of smaller engines. We are getting 120+ with OS 32s and 35s with Jett pipes and 8x7 props.

You're also wringing the snot out of those engines with those small props.

What size prop would you run on the me-109?




plAne NUtS,

Drypipe.

I have never used GMS engines, but the 8x7 will give you the best horizontal speed. The 8x7 will definitely run the engine at a higher rpm, but any engine should be able to handle it. I have run 8x7 on my TT .36 without any issues for several dozen flights.