Sea Level to High Altitude - What to Expect?

[AHP]

I’m looking for some insight from the all the high altitude fliers. I’m from FL and have been transplanted to the Denver area for the next 6 months (maybe permanently). I know the engines make less power and the air is thinner, but what should I really expect? Has anybody ever experience both relatively back to back? I’ve been here a little over a month and haven’t been able to do any flying yet. I’ll hopefully be maidening my new (to me) 40% Carden Edge this weekend. Is a 40lb 40% going to be a worthless brick here with a healthy 3W 150? The power to weight would be great at sea level, but how about at 5500ft? Should I try a prop other than the old trusty PT or Mezjlick 32x10? What octane gas should I run? I’ve always run 93oct and the highest available here is 91. Due the altitude, would it be beneficial to run a lower octane than 91? Any input would be greatly appreciated. I’m worried I’ve been too spoiled at sea level with year round flying and a near empty field.

I’m in the Englewood/Greenwood village for those familiar with the Denver area. I checked out a few local fields this weekend; Chatfield state park, the Mile Hi RC field in Aurora, and the BAS field on the Boulder reservoir. I didn’t get a chance to get to the Cherry Creek state park field yet. Provided the plane gets here this week and in one piece, I’ll probably go to Chatfield. If anybody wants to meet up, let me know!

[Divesplat]

I'm from Lubbock Tx (3500Ft) and experience a definate change from flying in Alb, NM (4500ft I think, same as Denver anyway)

You will notice:
1) Your engine has to be Leaner on the high end (less Barometric pressure which means less available 02 to mix with your fuel) I have noticed an extreme change in going to Dallas (900 Ft or so) the other direction. Run the motor but be prepared!!!

2) You will have to use MAXIMUM performance props to achieve the most with your engine.

3) All your control surfaces will need to be adjusted to more throw. When we go to Alb it takes several flights to get used to the ail/elev effects because there is a difference. Some pilots have gone so far as to adjust their ATV for high altitude flying. I think it just depends on what you get used to. Thinner air will cause less effect on the same deflection as well as poorer vertical perfomance and stall will occur at a higher airspeeed. Less lift on the wings as well. The heat will become more of a factor also.

Once you get used to it, it doesn't matter then, but if you fly at a lower altitude you will notice the difference.

Ed

[Supermod56]

Like Ed mentioned, you will have to lean the motor out a little, and go to a 32-12, I use that pitch in Idaho at 3000, took it to 4500 and noticed a difference in the controls, not too bad, you will get used to it. On the gas, stick with the good stuff.
Tom

[TimDavie]

From Oklahoma at 700ft. and went to the Love Air Fest in Greeley a few years back with a Carden Edge. It's like strapping 30 lbs. to the tail of the plane. I had a dead stick during the event due to my engine being too rich. Get a light plane and Leeeeeaaaaannnnn the engine. One of the United pilots that day said the density Altitude was around 9,000 feet. Garrett Morrison made it look simple that day with his 39% AW Extra. there was one other Carden there....a Cap with a bunch of lightning holes.

[hipollito]

I fly in Toluca Mexico 8500 feet, and yeah what these guys siad, its going to be harder for the engine to pull the plane, I always usea a bigger engine, for example u can do .60 with a 1.20 or showtime .90 with os 1.60, usually all .40 planes use .46 or .60 haven´t flown gas there so I cant tell you about that, right know Im flying at 1500 feet, because Im studying in another state, and I can tell its veeery different, for me its a lot easier to fly over here at 1500 feet, but you will get used to it and you are going to make some good responsive fingers..... you will notice that when you come back to flying in a low altitude field!!!

[AHP]

Thanks for the info, fellas; not all that encouraging.. Haha! The plane will be here tomorrow and I plan to be flying either Friday or Saturday. I'll definitely be retuning the engine before flying.

[ben_beyer]

I moved from about 350-500 ft. above sea level to 5000 ft. here in Fort Collins north of Denver. I knew I was going to loose power, but I was shocked at how much I lost. I'm moving back to a lower altitude...

[bodywerks]

Yeah, to give you an idea, I grew up in souther California and did most of my flying there. I got out of the flying aspect for a few years, but got back into it when I moved to Colorado Springs. Man, does it SUCK!!! I fell in love with flying all over again, but became so disgusted with the lack of performance that I am now in Tucson at a mere 2,000 feet, and the CRAPPY air AND weather in Colorado was a HUGE motivator to get me the he!! outa there...
Everything Divesplat said is pretty much true. I can tell you that at my field in Colo. Springs (6800ft elevation), an 8.5 pound plane with a YS 110 will not pull out of a hover. A 15.25 pound plane with a non-piped DA-50 will barely pull out of a hover, and the same goes with a 26 pound plane with a non-piped DA-100. In the Denver area, like Chatfield park, you can "get away" with about 27-27.5 pounds on a 100cc plane. It will pull out of an on-the-deck hover, but it will not be impressive by any means. As for 40%ers, I would say that you will be able to hover a 40 pound plane, but don't expect much on pull out.
You may want to consider full-length pipes, and you may also want to start looking for a new state to move to! This past winter, there were maybe 2 weekends when the snow didn't fall, the wind didn't blow, AND it was above 40 degrees. Come summer time, it get a litle better. But the wind still blows almost all the time, and as the temps go up, so does density altitude - good ol' catch 22!
Colorado's a pretty state, but it's HE!! on earth for 3D model airplane fliers!

[AHP]

I’m here on a contract for the next 5-6 months right now. There’s a good possibility I may be here permanently as the company I’m contracting for has mentioned a few times they’d like to hire me upon completion. I’m afraid they’ll make me an offer I can refuse.. Haha! I love everything about this area except for the altitude. The weather is supposed to be terrible this weekend so I may not be able to fly after all. I’m having serious withdrawals and to top it off, I forgot my sim software back in FL. Aaahhh! I don’t need to be able to rocket out of a hover; as long as it will pull out ok I can manage. I may have to invest in some lightening mods and if all else fails, 3W 170 here I come!

[TomLee]

At any of the local fields, we have plenty of people who can help with your adjustment to the altitude change.

At Chatfield, Jefcoaeromodlers have some world class fliers who are flying there. We can put you in touch with them. At Mile High, I also know of someone.

Aeroworks' office and warehouse is in Aurora, Co.

Not to worry, we can get you hooked up.

Tom

[AHP]

Hi Tom,

Between the rain, I got 2 flights in last Saturday and 2 on Sunday at Chatfield. I met a few nice guys out there that lended me a hand holding down the plane so I could retune the engine. I also met one of the guys from Aeroworks as well. I can't say I'm too happy with high-altitude flying.. The effects were to be expected, though. It's suprising to me how much quicker the plane flies. It screams in for landing where at sea-level it would be a walking pace. The power loss is very dramatic; my Edge strains to pull out of a hover. The engine is still a little rich but it's not going to make a significant difference. I need a 3W 170 now.

For giggles, here's a video from last weekend my girlfriend shot on my cell phone. The quality is pretty bad, it's better than nothing.

http://media.putfile.com/Carden-Edge-540-at-5500ft-ASL

I'm getting ready to head out to the field today and will be there all day tomorrow as well. If you make it out, introduce yourself. You can't miss my plane.

Abram

[TomLee]

Will not be at the field today, MY grandaughter is getting married andI have the honor of giving her away. Do not expect to be out until Monday.

Watched the video, great flying.

I am sure you checked the RPM's and temp. I fly smaller engines, but I find that if I use 15 to 20% smaller diameter props, I do very well in meeting the mfg's specs.
IE: 14 X 6 at sea level, 13 X 6 here. Naturally there will be varying opinions.

Most of us use the larger engine that is listed on the box for a given airplane. Once you get used to the higher landing speeds, all will be just fine. That is one reason the runways are 650 and 750'. The turbines like the length also.

Expect to see you at our IMAC event in July.

www.jefcoaeromodlers.org

Tom