Mb339 Landings
10-17-2002, 04:41 PM
#1
Mb339 Landings
MB339 LANDINGS
This jet flys extremely well but landings are a site to behold. This jet does not bleed off air speed well and by the time you reach the ground it's ready to fly again. Has anyone thought about a speed brake? If so how and where? I do not think oleos would solve this problem.
P. Richards
Mach 2 Jets
Flight Demonstration
Technical Representative
This jet flys extremely well but landings are a site to behold. This jet does not bleed off air speed well and by the time you reach the ground it's ready to fly again. Has anyone thought about a speed brake? If so how and where? I do not think oleos would solve this problem.
P. Richards
Mach 2 Jets
Flight Demonstration
Technical Representative
10-18-2002, 06:17 AM
#4
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Join Date: Oct 2002
Location: Uk Sandhurst
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Crow Brakes
I am using crow braking to slow mine down to safe landing speed so far all my landings have been successfull. I set the ailerons to 10mm uptravel and flaps lowered to 31mm also mixed in is 5% down elevator. With my P80 set to 35000 idle you just need to line her up about 400 yards out and let sink to the ground keeping the glide angle as flat as possible (Try to avoid high angles of attack as this seems to start the bounce) I hope this helps.
10-19-2002, 08:06 PM
#7
Landings
Plasmavortex may have the right answer with the Crow set up and is definitely correct about high AOA causing the bounce.
My experience: For me, the 3/16" Springair gear effectively is a pogo stick. After 75 landings with about half having a serious bounce and a final cartwheel I changed out the gear for oleo's. Thirty flights later, I've had only one bounce that was noticeable and it was because I was way slow. What I've discovered is that the airplane can be slowed down too much. It needs to be landed a touch fast, or at least without the stick on the stop. With some small speed above stall, say 5 mph, the oleo's take all the fight out of the touchdown.
My set up is with 2" of flap travel at the TE at the root. Gives a bunch of drag and with any wind at all, it needs power for the approach, even with the P80. The Crow setup might be even better.
My $.02
My experience: For me, the 3/16" Springair gear effectively is a pogo stick. After 75 landings with about half having a serious bounce and a final cartwheel I changed out the gear for oleo's. Thirty flights later, I've had only one bounce that was noticeable and it was because I was way slow. What I've discovered is that the airplane can be slowed down too much. It needs to be landed a touch fast, or at least without the stick on the stop. With some small speed above stall, say 5 mph, the oleo's take all the fight out of the touchdown.
My set up is with 2" of flap travel at the TE at the root. Gives a bunch of drag and with any wind at all, it needs power for the approach, even with the P80. The Crow setup might be even better.
My $.02
10-19-2002, 09:26 PM
#9
Oleo's
Well, they don't fit. I'll have to make some mod's.
I used the black light airplane knee action struts (15082/000) from Eurokit Planes in Canada. They're too big by about an inch too long. I just got a set of Robart 550 retract units which may take the struts after I cut them and the wheel wells won't need too much of a mod (I hope). Eurokit has another smaller set (15072/000) that just might work better in these retract units.
More details here: http://www.RCUniverse.com/showthread...highlight=Thud]
I used the black light airplane knee action struts (15082/000) from Eurokit Planes in Canada. They're too big by about an inch too long. I just got a set of Robart 550 retract units which may take the struts after I cut them and the wheel wells won't need too much of a mod (I hope). Eurokit has another smaller set (15072/000) that just might work better in these retract units.
More details here: http://www.RCUniverse.com/showthread...highlight=Thud]
10-19-2002, 09:30 PM
#10
Join Date: Jan 2002
Location: Sydney, , AUSTRALIA
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MB339 Oleo's
Ditto- what Nick asked which type of oleo's for the Cermark MB339? I ordered the Australian M.A.S. units but they do not fit unfortunately!
And what AUW does your MB339 fly at?
This model should land quite slow in theory! with its good wing area and large flaps...
Tam has also flown his MB339 with a RAM500 @ AUW of 21 lb, this shows that the model can handle some weight, and fly well on the wing with only 11 Lb of thrust. Strange that it should need to land fast, unless you have a seriously heavy MB339.
And what AUW does your MB339 fly at?
This model should land quite slow in theory! with its good wing area and large flaps...
Tam has also flown his MB339 with a RAM500 @ AUW of 21 lb, this shows that the model can handle some weight, and fly well on the wing with only 11 Lb of thrust. Strange that it should need to land fast, unless you have a seriously heavy MB339.
10-19-2002, 10:33 PM
#11
AUW
My MB339 ARF is 17.5lbs dry and 22.5lbs fully fueled and has a P80. Don't know if this is overly heavy, but I also don't know where I could have saved any serious weight. I used 2 x 2000 mah batteries in the nose to get the Cg and they are a little heavy.
The airplane will land very slow, its just that if you do that, and it touches down the least "heavy", the struts just toss you back up. And that's when you find out just how much energy is really left in the airplane and you also become a spectator. It could easily just be the nose gear that needs the oleos because if the nose hits "heavy" it pitches the airplane up. Generally, all this is usually indicative of an aft Cg relative to main gear location or lack of positve nose incidence. I reseqenced my fuel so the weight is forward at landing. It helped. My nose incidence is slightly negative, so that's probably bad.
The oleo's fixed most all of it, and even "faster" landings only encounter a very slight "skip" to a second good touchdown.
The airplane will land very slow, its just that if you do that, and it touches down the least "heavy", the struts just toss you back up. And that's when you find out just how much energy is really left in the airplane and you also become a spectator. It could easily just be the nose gear that needs the oleos because if the nose hits "heavy" it pitches the airplane up. Generally, all this is usually indicative of an aft Cg relative to main gear location or lack of positve nose incidence. I reseqenced my fuel so the weight is forward at landing. It helped. My nose incidence is slightly negative, so that's probably bad.
The oleo's fixed most all of it, and even "faster" landings only encounter a very slight "skip" to a second good touchdown.
10-20-2002, 12:31 AM
#12
Mb339 Landings
Things are looking up I've got three more flights logged with two greased landings. I set up my approach with a long low glide path going to idle on the stick as the jet turns final. This combination seems to be working just fine. I am keeping it level and no flare.
P. Richards
Mach 2 Jets
Flight Demonstration
Technical Representative
P. Richards
Mach 2 Jets
Flight Demonstration
Technical Representative
