Jugmaker

Hi, What is the average take off distance for 40 size trainer on grass? Would larger wheels help or just slow the plane down? Any suggestions on type of grass and height to mow?
Jugmaker

Pilot Chad

My Feedback: (4)

i would say 60 feet, but you still need flat land for the climb out..

echobot

I fly off of grass and larger wheels do help with the take off. I guess I use up 100 feet or more with the grass I fly off of.

Pilot Chad

My Feedback: (4)

yea, i was thinking of taildragger, cause thats all i have flown... but, the wheels should help, i also think the rubber wheels will help alot

bubbagates

My Feedback: (32)

50 - 100 feet and the wheel size, type and engine size and prop size and pitch can all play factor in that. Heat, humidity, and your altitude above sea level all play a factor in it too. The more heat and humidity, the less power the engine will make and the less air the prop will bite into. Altitude above sea level also reduces engine power and prop bite (thrust)

As an example at 400 feet above sea level on a 60 degree day. My old LT-40 with an OS46AX turning an 11X5 APC prop on 3.25 inch rubber wheels taking off at full throttle in grass cut at 1.5 inches and smooth would be in the air and climbing out in a 15 degree climb in around 60 feet, give or take 5 feet. Change the prop to a 12,25X3.75 and you can cut the figures by 1/3. This is not a precise measurement, just using the fences we have at the flight line as an estimate.

Fastsky

I have tried various sizes of wheels on our grass field which looks great but is quite rough. The magic number is 3" for the mains. If the front tire is 1/4" smaller than the mains then use 3" for the mains and 2 3/4" for the front tire. If all 3 are the same size then use 3" all around. I tried up to 3 1/2" and actually found that the larger wheels were too hard on the landing gear if they hit something. The smaller 3" size worked better. I had a takeoff run with my Sea Fury and hit a gopher hole with 1 of the wheels. It just bounced over the hole on that side and kept going! If the wheel had been smaller it would have dug into the hole and damaged the plane! [8D]

Jugmaker

I think tire size will make a big difference. Where I fly from is pretty rough now.We are trying to get it in better shape, but it is hard to do much in winter.
Thanks to all.
Jugmaker

Pilot Chad

My Feedback: (4)

Well, Today my plane almost ran off the runway cause the steering is horrible when you get to take off speeds, So, We were at full ground speed and did it in the width of a 2 lane road, (a pretty wide one). Pretty cool that it all went well though

exeter_acres

My Feedback: (2)

With full throttle.... you can get a trainer in the air pretty quickly.... it is the landing that needs more space....

Pilot Chad

My Feedback: (4)

Exeter, Very true,

Jugmaker

I have about 300-350ft. of runway,is that enough to land on?
Jugmaker

propbuster

My Feedback: (1)

Bubbagates is right. Density altitude changes things. When I was in my full scale training we were taught The three H's. High, Hot and Humidity. Your engine will not perform as efficient when the air is hot and humid as well as if you are higher up from sealevel. You will need a lot more room to take off from say, Denver on a summer afternoon than Long Island NY on a cool fall day.

sandal

Another thing to look at is the landing gear. "Tweaking" the gear a little can make a big difference. My £.02:

Main gear:
To get the shortest possible takeoff distance, the main gear should be just behind the CG. If the landing gear is too far aft, the airplane will need much higher speed before the elevator can push the tail down and lift the nose. If the landing gear is just behind the CG, you can lift the nose slightly as speed increases. This will produce a little lift and take a little weight off the wheels, reducing "grass drag". As speed increases, the wing produces more lift, taking more weight off the wheels, and - the plane will lift off gently. It takes a little practice, but looks like the real thing, and the takeoff is very stable and predictable.

Nose gear:
Too short (nose down) will make the plane stick to the ground on landings, but will require higher speed for takeoff. It will most likely also lift off more abruptly. Too long (nose up) will make the plane easy to take off, but it might bounce more on landing. IMO neutral (airplane level) is the best setting.

Runway:
300 ft is more than enough for a .40 trainer - IF you fly it well. Takeoff won't be a problem, but I agree with exeter; Landing needs more space. With practice, a .40 trainer can be landed (and stopped) on a 75 rwy - but in order to do that, glidepath, speed, etc. have to be close to perfect.

Landing approach:
My "landing approach" was to fly in the opposite direction of the runway, cut the throttle to idle and let it glide down during the 180 degree turn back to the runway. It brought the plane down safely, but I had to "aim well" to land where I wanted to. We fly off a 2200x75 ft full size grass airfield, so this wasn't a problem . Last summer I began experimenting with landing like full-size aircraft: Elevator controls airspeed. Stick forward will increase speed, stick back will reduce speed. Throttle controls sink rate. I try to maintain constant speed with my elevator, and if I see that I will land short, I increase the throttle slightly. If it looks like I'm going to overshoot, I reduce the throttle a little. This method has made my landings more precise.

I have probably given you information in my post that you didn't ask for. I thought it could be a good idea to share some of the things we have learned in our club, as we fly mostly trainers on a grass field.

Jugmaker

Sandal, No it was not to much information(maybe not enough). The landing is where the problem may arise.There is not a lot of distance at the ends of the runway.The trees are pretty close and you know how they like to eat airplanes.Will try to post some photos of the runway on my web page soon,haven't got it finished yet.

Thanks
Jugmaker

Pilot Chad

My Feedback: (4)

As i said, Unless you are a great pilot and can turn out of the take off, You need room to climb out. But you should have it with 375 feet

bubbagates

My Feedback: (32)

newbtoRC

This is actually a very basic skill and one your instructor should be teaching you.

To do this just keep the plane on the ground a little longer to get a good amount of speed up (do not let it takeoff when it's ready, you tell it when to takeoff and start at the very beginning of the runway), climb out and at the same time turn the way you need to, keep the climb as shallow as possible to keep the airspeed up and the plane accelerating and the bank angle enough to do what you need to clear the obstacle.

Pilot Chad

My Feedback: (4)

bubba, Thanks, I haven't taken off yet so we haven't quit gotten there. But I will learn soon enough. Jug maker, Here is a pic of a landing that was dead stick, No speed. This was taken about half way from the beggining of the runway, a good bit further from begging of approach. Oh and this is right at touchdown

bubbagates

My Feedback: (32)

newb,

I was just concerned that you mentioned it takes a great pilot to do that type of takeoff and that could lead someone to believe that it was a complicated manuver which it really is not. It's no big deal just something I picked up on.

Keep up the good work on your training.

Chevelle

My Feedback: (2)

This happened to a couple of guys at our club. They fly hot aerobatic planes with symetrical wings, trike gear and tiny wheels. When the grass get just a little too long or is damp, they run the whole length of the field, engines screaming, going no where. It's kind of funny really but I'm sure frustrating for them. With so little lift coming from the airfoil, the only way they get into the air is by increasing the angle of attack. With not enough airspeed because of the grass, no lift. They usually get around it by fiddling with their front gear, extending it as much as they can to get some angle in there. It's one of the more entertaining aspects to spring!