hi..
my friend onur bolel finished this plane;and goes over 135 mph!!

What engine/prop combo does he have in it? I've got the same plane with a Saito 100 turning a 13X10 APC prop and clocked it at 128 MPH. That temp that day was a bit cool, so when it warms back up, I can probably get a higher speed out of it.

John

Things that impede performance: Hot, High and Heavy
Things that improve performance: Cold, Low and Light
A warmer day will slow you down, not speed you up.........

I totally disagree. Cold air, more dense. Hot air, more thin. Cold air, much more drag. Hot air, lots less drag, enabling higher speeds. Not just my opinion, it's a fact!

Yard Dart,

Engine performance is DIRECTLY related to air temperature. Hot days= less performance.
This is a fact!!!!

The reduced performance from hotter temps with the engine and the propeller far outweigh the reduced drag on the airframe due to less dense air mass. Again another FACT!!!!!!!

Dang you a fast typer Dewalt 17 I was about half way through my response when I saw your post, I'll just half't to agree with you and save myself some typing.

SO if I turn my furnace up to high, will my typing speed up or slow down???Sorry I just could not resist!!!!!!!! a thread about Hot Air just begs for one liner comebacks LOL

I TOTALLY AGREE! AND THAT'S A FACT!

I seriously doubt this.

It is a fact the engines peforme better in cooler weather to some extent. If have a carbuerated engine and its 65 below out then its gonna be a bear to start, tune, and keep warm. also its gonna put more wear on the engine.

DUH?????

DOUBLE DUH????

Hay...has anybody ever heard of Turbo Charging...How about cold, low pressure air...like at 30K or higher ?

The only way we were able to keep our 2-strokes running in Bethal, Alaska in mid winter...-20 f., was to keep our models in a heated van...then start our engines in that van, run them up to 100%, take the models out of the heated van and launch the model. As long as you kept your 2-stroke at full power, the engine ran. Blew some awesome smoke trails...and the smoke trails would stay put for hours...and even days. Talk about still air. Wierd stuff happens to our models with this kind of cold. But we flew !

If you can spit and it bounces when it hits the ground...it's to cold. Maybe that is why I now call Maui home...

So much for the GP Shoestring...

Soft landings always,
Bobby of Maui

How about... Nice plane... I have one too... [&o] 61 2stroke... Moves right along pretty fast, but not at warp speed... I'm envious... Still Love the Plane. One of my favs.

There is no argument from me that an engine runs better in cooler temps than warmer ones, but I will not back down from this fact.... Two different planes clocked with a radar gun around September, a Sig Kougar with a Picco .40 (127MPH) and my Shoestring (128MPH). January, same planes tuned to max performance. Kougar, 118 MPH, Shoestring, 120 MPH. These are the facts, but you can call them what you want. Drag from air density is definately more of an affect on air speeds than the affects of air temps on an engine's performance. One thing is for sure, when the air temps here get back up, my planes' speeds will pick up. And one other thing, the faster speeds, the ones recorded on the warmer days, were achieved by engines that were running "rich". Since they were indeed running rich, they were running much cooler than an engine that someone may be running a bit more lean. So, a rich engine running cooler in the summer opposed to the same engine that is run more lean in the winter months should probably be running very close temps. So, what caused the difference in air speeds? Air density! It's not rocket science fellas, it's common, everyday knowledge.

Well, a Supertigre .90 turning a 12-9APC at 4500 feet altitude only gets about 111 mph here in Logan Utah, Its about the best I can get. 138 mph............ maybe in a vertical dive.[&o]

An engine may run better in warmer temps but a prop has less air density to bite into. During the winter flying I notice 2 things, first my engine has to be alittle fatter and second the planes glide a whole lot better.

Magnum .91 XLS , no exhaust- just a header, %15 nitro, speed is around 130 mph. Prop is 12x12. Don't ask me how loud it is, I can't hear you : )

What you guys are arguing over you are missing something. Yes, an engine will develop more power with cold air as compared to warmer air. This is fact. Cold, denser air yields more power. (thats why some turbocharged engines have an intercooler. compressed air from the turbo gets hot so the intercooler cools it prior to combustion for more power)

However, airframes fly at faster TRUE airspeeds in warmer air (less dense air). So even though the engine is making more power on a colder day, the aircraft will not be as fast as on a hot day. (ever notice how slow you can land your plane on a real cold day, and how in hot day it needs faster (true) airspeed to land and takeoff?) This has a lot of variables in it, but that is the basic. Even though full scale normally aspirated airplanes may cruise at only 60%-70% of full power when high altitude, the thin air at altitude yields higher true airspeeds (for any given indicated airspeed). This effect or concept is true at all altitudes. If it is warmer at any given altitude, even sea level, the warmer the air the faster the true airspeed and vice versa. (thats why planes cruise high up in less dense air (even though it will be very cold up there at altitude), they go faster on less fuel than can be done lower thus increasing range/safety, etc.)

For model planes the hotter thin air will increase speeds more than the slightly higher power output of the engines in colder air. If the engine can tach out at the same rpm at both temps, then the plane will be faster in the warmer air. The effect of warm thin air true airspeeds has a greater effect on speed increase than the engine power increase associated with cold(er) air.

How hard is this thing to land. I'm guessing it's hotter than hell.

The plane is a great plane to fly... No bad tendencies... But is doesn't like to slow down... comes in fast... Though I fly off grass and when it does set down... It's like it has air brakes and comes to a stop pretty fast... Just have to have the %*!!$ to set down and know it will stop... My runway east / west is 250 ft... and each end has 10- 15 ft of brush at it...

The WM Midget Mustang does the same thing. I simply fly a low approach angle and i have no problems

I want to thank Shoestringracer for backing me up, he's one of the few that knows what he's talking about. I tried to tell some of these yahoos the same thing in post #4 and #14, but you've got some guys out there that will argue with a road sign. Anyway, thanks Shoestring, maybe some of these guys have actually learned something, and then again maybe not. Some men you just can't reach!

John