Pod installation

Tell all about your Lazair
Post pics --
After a while we wil streamline the forums and see what is most popular.
Want you own forum ? Let us know.

Postby Guest » Thu Apr 07, 2005 9:06 am

Repost from LazairFlyers Group for Posterity :

Hi Guys,

I'm glad that this has sparked some discussion. Mark, I did see a
Lazair at the UPAC convention two years ago that looked very similar
to yours. I would suspect that it was a retrofit from some other
ultralight. There are a few of these small pods available from
different suppliers. I believe that Leading Edge Airfoils still
stocks some, you might check their catalogue and see if what they
have is close to yours. At any rate, there is another Lazair out
there with a similar set up and it does fly. So, not to worry.

Thanks for all of the input so far. It certainly creates some
comfort knowing that my situation is not so unusual. The pitch down
effect with power off did give me a scare, but I think it is sorting
itself out now. What I have done is added much larger trim tabs. I
flew it last night, (crow hops) and have found much better stick
forces. It was windy and a bit turbulent, so I couldn't properly
fine tune the tabs. I'll keep you posted on the final results the
next calm day. Tonight I will do some more weight and balance
calculations. The pod only weighs 4lbs so I doubt if it's a real
issue. Might end up putting 1lb at the tail. When I first
installed the pod, I had about 4lbs added to the tail at a guess,
but it made very little difference and I had to add trim tabs
regardless. The airplane is very light and pitch sensitive. So I
believe the situation is more aerodynamic than weight related.

For any windshield/pod, there will be some downward force created by
the windshield. If the pod can be mounted pointing slightly upward
to counteract this force, I think that is the best option. Mike's
pod is designed to be mounted level with the frame, so the trim tabs
need to balance the forces at the elevator. My feeling with the
larger trim tabs is that the downward force increases with airspeed
so the tabs must become more effective with airspeed as well. The
problem is that balanced flight with power on may cause the tabs to
be less effective with power off because they no longer have the
extra force of the propellor blast for leverage. I've mounted mine
on the upper portion of the elevators, (away from some prop blast)
and, in making them larger, hope that they will have the leverage
required power off. It seemed to be working last night as I was up
to 45mph power off and the nose wanted to rise, not drop.

The tail wag was what scared me quite a bit at first because I
didn't know if something was wrong in the airplane or what.
Everything is tight, and I've flown it without the pod with no wag
at all. So, at least it's confirmed that it's aerodynamic. There is
sloppy air coming off of the pod, perhaps in combination with the
wing when nearing stall speed. This is shaking the tail. Now that I
know what it is, it's not so bad. It's kind of like having a stall
warning device. Now I know that application of power or increased
airspeed will stop the shake. There is no tail wag at higher
speeds, which would be very dangerous indeed. My windsheild is very
narrow, so I don't know how I could do much more. Perhaps a fairing
behind my head as suggested might help.

The Lazair was designed to be left open, so any additions will
change it's handling characteristics. On the plus side, WOW!!!! I
flew without the pod last week just to confirm that the bird is
fine. It was startling! I've gotten so used to the pod that I
didn't realize the performance difference. Without the pod, I climb
at about 200 fpm. With the pod, it's 400 to 450 fpm! Without the
pod, I barely reach 40 mph at full throttle and to maintain level
flight, require 3/4 throttle minimum. I cannot maintain level
flight with one engine. With the pod, I exceed 45 mph full
throttle, and can maintain level flight with less than 1/2
throttle! This has got to mean longer engine life, and certainly
lowers the fuel consumption. In fact, to lower the wear on the
engines after takeoff, once at 250ft, I usually reduce throttle to
3/4 and cruise climb to altitude at 200fpm! I can also maintain
level flight with one engine! Around here, there are more cooler
days in the year than warm ones. The reduction in wind chill is
dramatic without taking much away from the feeling of the open
cockpit. If you're considering a pod, I say do it! It sure makes
the airplane a much better performer. But take your time trimming
it out and expect some of the situations discussed. Keep the
windshield as narrow as possible to keep the effect to a minimum.

I'm hoping to have my bird balanced out this week. I'll keep you
posted of what worked and what didn't as I go.

Thanks,
Brian
Guest
 

Postby Guest » Thu Apr 07, 2005 9:16 am

Now add some P-tips and make another "big discovery".


"The Lazair was designed to be left open, so any additions will
change it's handling characteristics. On the plus side, WOW!!!! I
flew without the pod last week just to confirm that the bird is
fine. It was startling! I've gotten so used to the pod that I
didn't realize the performance difference. Without the pod, I climb
at about 200 fpm. With the pod, it's 400 to 450 fpm! Without the
pod, I barely reach 40 mph at full throttle and to maintain level
flight, require 3/4 throttle minimum. I cannot maintain level
flight with one engine. With the pod, I exceed 45 mph full
throttle, and can maintain level flight with less than 1/2
throttle! This has got to mean longer engine life, and certainly
lowers the fuel consumption. In fact, to lower the wear on the
engines after takeoff, once at 250ft, I usually reduce throttle to
3/4 and cruise climb to altitude at 200fpm! I can also maintain
level flight with one engine! Around here, there are more cooler
days in the year than warm ones. The reduction in wind chill is
dramatic without taking much away from the feeling of the open
cockpit. If you're considering a pod, I say do it! It sure makes
the airplane a much better performer. But take your time trimming
it out and expect some of the situations discussed. Keep the
windshield as narrow as possible to keep the effect to a minimum.

I'm hoping to have my bird balanced out this week. I'll keep you
posted of what worked and what didn't as I go."

Thanks,
Brian
Guest
 

Postby rayjb60 » Thu Apr 07, 2005 10:08 am

I'd like to get a performance increase like that as well but don't want to lose tail effectiveness at lower speeds.

What do you think is the big drag on the Lazair without the pod?

My guess would be; Pilot, and all the tubes around the nose/floor area, all the stuff around the seat/pilot/tank area.

With those areas in mind I think a streamlined fairing behind the pilot/seat/tank Plus the floor of the pod to the nose area would be beneficial.

Im thinking that a narrow half height windshield would be the best of both worlds.

This way the high presure air on the underside of the wing is not disturbed as much by turbulence and is able to flow back to the tail.

I'll make my own pods and fairings and report on its effectiveness before and after.

I think some wool yarn tufts taped on the area of the wing around the pod might reveal some interesting facts about the airflow, if anyone cares to do that and report back to us here.

I think that those with the full height windscreen could help tail effectiveness by putting a fairing behind the pilot to help reduce the turbulence or to narrow the top of the windscreen or better yet shorten it.

Tail shakes is a sure sign that your control is being reduced by turbulence.
<H5>Nothing is impossible...Even the word tells you Im-Possible!!!</ H5>
User avatar
rayjb60
LazairNUT
 
Posts: 235
Joined: Tue Jun 15, 2004 2:49 pm
Location: Lake Elsinore, CA

Postby bdiedenhofen » Fri Apr 08, 2005 1:43 pm

Looks like I've got it all sorted out now. I added one pound of lead to the tail, and installed larger trim tabs on the upper portions of the elevators. I did a few crow hops to get the tabs set right and did not need very much down deflection at all, much less than I did with the previous, smaller tabs. She now flies hands off at 30 mph. Higher up on the elevators seems good as there is virtually no noticable difference between power on and power off. I had no tail shake, I think its a very specific speed somewhere below 30 that induces it. One benefit that I hadn't considered is that with the larger tabs, I have increased the surface area of the elevators a bit. In the flair, where I lost a little control effectiveness due to blanketing from the pod, I now have a much stronger control response.

Life is good, the plane handles great, the performance is vastly better than podless and I can sleep at night knowing that I now understand what was going on.

Brian D.
bdiedenhofen
Popular Lazair Member
 
Posts: 65
Joined: Sat Oct 11, 2003 7:55 pm

Postby Shannon » Sun Apr 10, 2005 11:33 pm

Robs Bubble Fairing
You do not have the required permissions to view the files attached to this post.
Shannon
SHANNON
 
Posts: 1082
Joined: Thu Jan 15, 2004 10:05 pm

Postby Guest » Mon Apr 11, 2005 6:09 pm

Side View
Guest
 

Postby Shannon » Mon Apr 11, 2005 6:11 pm

Side
You do not have the required permissions to view the files attached to this post.
Shannon
SHANNON
 
Posts: 1082
Joined: Thu Jan 15, 2004 10:05 pm

Postby JPXman » Fri Sep 02, 2005 12:12 am

while on vacation i was visiting with my mother, and while cleaning her garage for her, i found my old man's lazair photo album from back in the day! I inherited JCP from my dad and always wondered where his pictures were, well i found them. Here are a few gems from the album - and these next few pictures are all TWO SEATERS - that's right!

First, C-IEFS: owned by Pete bonell, a 2-seater with KFM's and a custom EC
**warning, file size is over 2.5Mb to keep the quality good. the picture was taken from afar
***this lazair now owned by Larry Fish I'm pretty sure
You do not have the required permissions to view the files attached to this post.
User avatar
JPXman
LazairNUT
 
Posts: 625
Joined: Sun Nov 02, 2003 10:15 pm

Postby JPXman » Fri Sep 02, 2005 12:15 am

Second:

C-IFII: owned by D'Arcy Seguin, and now i own the pieces of her :( some hoodlums on the lake thought they'd steal it, so they untied it, attached it to a boat, and tried to tow it away. at 10mph the lazair became airborne, cartwheeled and disintegrated as it tumbled along the surface. but it lives again in these next two pictures! JPX engines with tuned exhaust system!
You do not have the required permissions to view the files attached to this post.
User avatar
JPXman
LazairNUT
 
Posts: 625
Joined: Sun Nov 02, 2003 10:15 pm

Postby JPXman » Fri Sep 02, 2005 12:16 am

same plane, different angle. all these shots were taken at my cottage in 1986 (I was 12 at the time :)
You do not have the required permissions to view the files attached to this post.
User avatar
JPXman
LazairNUT
 
Posts: 625
Joined: Sun Nov 02, 2003 10:15 pm

PreviousNext

Return to Pilots Lounge

Who is online

Users browsing this forum: No registered users and 3 guests

cron