H9 P-51 Mods
05-13-2003, 01:36 PM
#1
H9 P-51 Mods
I'm going to buy a H9 P-51, but would like to change the color scheme a bit to make it a bit more "mine". How hard is it to remove Ultracote (specifically the tail) and recover with silver or remove the "Q" decal from the side? Anyone tried this? I can build a new fin and stab very easily since they're just flat framework. Might be better to sheet the stab anyway, as I have heard of some flutter problems. Would it be more practical just to spray the tail with Lustercoat or similar?
05-13-2003, 09:31 PM
#2
Member
Join Date: Feb 2003
Location: ROCKWALL, TX,
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
H9 P-51 Mods
"Not intentionally" :-)
What I mean is I did remove much of the horizontal covering and half of the wing - due to a less than adequate take-off many weeks ago and resulting repairs....
It actually comes off just fine. I did not try removing the Q because the vertical wasn't damaged but removing the stripes etc. on the wing went fine- same thing. With the parts not glued in place - new out of the box, your color change would be quite easily accomplished. I have read one post regarding flutter and the tail assembly. I believe that individual was running a very large engine i.e. in excess of the Saito 100. I myself with the 100 have had no flutter problems and really enjoy the way the AC flies. I did "mod" the horizontal to strengthen during repairs, but only to facilitate my tail dragging warbird take-off "learning curve".
Best of luck, you will love the H9. Do change the landing gear though. The stock wires are too flimsy for the AC. Probably the most posted/recommended mod to this ARF.
Smitty
What I mean is I did remove much of the horizontal covering and half of the wing - due to a less than adequate take-off many weeks ago and resulting repairs....
It actually comes off just fine. I did not try removing the Q because the vertical wasn't damaged but removing the stripes etc. on the wing went fine- same thing. With the parts not glued in place - new out of the box, your color change would be quite easily accomplished. I have read one post regarding flutter and the tail assembly. I believe that individual was running a very large engine i.e. in excess of the Saito 100. I myself with the 100 have had no flutter problems and really enjoy the way the AC flies. I did "mod" the horizontal to strengthen during repairs, but only to facilitate my tail dragging warbird take-off "learning curve".
Best of luck, you will love the H9. Do change the landing gear though. The stock wires are too flimsy for the AC. Probably the most posted/recommended mod to this ARF.
Smitty
05-14-2003, 05:51 PM
#3
My Feedback: (8)
Hangar 9 P-51 Mods
I believe I am that person referred to in the above post. I have an OS 1.20 Surpass III in this plane. Engine size is irrelevant when discussing flutter and I will explain why. Airspeed is somewhat more relevant but only from the standpoint that flutter usually occurs at higher airspeeds. In my posting about the flutter problem, I clearly stated that the flutter was occurring at about HALF THROTTLE (this was on it's first test flight so it hadn't been opened up yet). I estimated the speed to be about 80 mph (is that faster than a Saito 1.00 at full throttle?). The horizontal stab tips on mine were a blur as the plane went by. I tore out the original stab and made a new stab and elevators out of solid balsa sheet. Flutter problem is gone. Full power, no flutter, 30% nitro, still no flutter, around 125mph, still no flutter. No flutter whatsoever, even in a full power dive.
So then, was it the fact that I have a little larger engine than the size recommended or was it the poor construction of the stock horizontal stab? Flutter isn't caused by airspeed, at least not by any airspeeds you are likely to ever attain with this airframe. The usual culprits that allow flutter to happen are either poor/inadequate design, poor construction, or sloppy linkages between the surface and the servo. In solving this problem, I didn't change anything about the linkage I was using; learned many years ago how to set up linkages correctly. When I took the covering off the stock horizontal stab, I found the balsa to be extremely light, bendy and twisty. The construction of the stab should have been sufficient but the choice of wood for this application was poor. The bendy, twisty part was the cause of my flutter.
We aren't hearing a lot of problems with these stabs so I figure my problem was the exception rather than the rule. You may be just fine with the stock horizontal stab on yours as long as you satisfy yourself that it is sufficiently rigid.
I did not replace the vertical stab or rudder since they seemed rigid enough even though the vertical stab is open framework construction very similar to the horizontal stab. A lot of hard flying since then has proven this was a correct decision.
Since you are going to re-cover the stab anyway, I would suggest that you at least soak the balsa with thin CA to make it stiffer than it already is. Sheeting it would be an even better bet. If you decide to sheet it, I would choose a fairly dense balsa sheeting. The stiffer the stab is, the better off you will be.
Another tip to help eliminate the possibility of flutter in your surfaces is to seal the hinge line. Since you are going to recover the plane anyway, cut strips of the covering material about 1.5 inches wide and the same length as the hinge line and iron them into the hinge gap area. This will also make the surfaces more efficient. I am in the habit of sealing mine both top and bottom.
One more example of engine size irrelevancy as far as causing flutter. A friend of mine has a Great Planes P-51. This is a considerably smaller airframe. His is equipped with a YS 1.40 Supercharged 4stoke which puts out way more power than my OS 1.20 Surpass. He is turning a 14" diameter 4 blade APC prop (not sure of the pitch but I believe it is a 14X12) and averages speeds in the 145 to 150 mph range. It is even faster with a 2 blade prop. There has never, ever, been any flutter on this airframe. This is an airframe built stock according to the plans. In my opinion, the GP P-51 is a much better designed structure than the Hangar 9 ARF. It's design includes solid balsa sheet horizontal and vertical stabs as well as elevators and rudder. While the construction of the stabs on the Hangar 9 seem to be working in all but a few examples, such as the problem I had, I still believe it to be inadequate for an airframe of this type and size. It is interesting to note that the soon to be released larger Hangar 9 P-51 (77" span) does not have this kind of construction on the stabs. It has fully sheeted, airfoil shaped stabs. I believe the original Hangar 9 P-51 should have had similar.
Now, lest anyone get the wrong impression about this airframe, I want to make it clear that what you have when ready to fly this plane is one of the sweetest flying, no bad habits airplanes you could ever wish for. Mine is a little heavier than most at 11 lbs but this plane's performance and flying characteristics are not hampered at all because of the weight. Mine glides a phenomenal distance to an extremely light and slow touchdown. As a former pylon racer and current jet pilot, I tend to really wring mine out every time I fly it. Except for that initial flutter problem, it handles easily anything you can put it through.
So then, was it the fact that I have a little larger engine than the size recommended or was it the poor construction of the stock horizontal stab? Flutter isn't caused by airspeed, at least not by any airspeeds you are likely to ever attain with this airframe. The usual culprits that allow flutter to happen are either poor/inadequate design, poor construction, or sloppy linkages between the surface and the servo. In solving this problem, I didn't change anything about the linkage I was using; learned many years ago how to set up linkages correctly. When I took the covering off the stock horizontal stab, I found the balsa to be extremely light, bendy and twisty. The construction of the stab should have been sufficient but the choice of wood for this application was poor. The bendy, twisty part was the cause of my flutter.
We aren't hearing a lot of problems with these stabs so I figure my problem was the exception rather than the rule. You may be just fine with the stock horizontal stab on yours as long as you satisfy yourself that it is sufficiently rigid.
I did not replace the vertical stab or rudder since they seemed rigid enough even though the vertical stab is open framework construction very similar to the horizontal stab. A lot of hard flying since then has proven this was a correct decision.
Since you are going to re-cover the stab anyway, I would suggest that you at least soak the balsa with thin CA to make it stiffer than it already is. Sheeting it would be an even better bet. If you decide to sheet it, I would choose a fairly dense balsa sheeting. The stiffer the stab is, the better off you will be.
Another tip to help eliminate the possibility of flutter in your surfaces is to seal the hinge line. Since you are going to recover the plane anyway, cut strips of the covering material about 1.5 inches wide and the same length as the hinge line and iron them into the hinge gap area. This will also make the surfaces more efficient. I am in the habit of sealing mine both top and bottom.
One more example of engine size irrelevancy as far as causing flutter. A friend of mine has a Great Planes P-51. This is a considerably smaller airframe. His is equipped with a YS 1.40 Supercharged 4stoke which puts out way more power than my OS 1.20 Surpass. He is turning a 14" diameter 4 blade APC prop (not sure of the pitch but I believe it is a 14X12) and averages speeds in the 145 to 150 mph range. It is even faster with a 2 blade prop. There has never, ever, been any flutter on this airframe. This is an airframe built stock according to the plans. In my opinion, the GP P-51 is a much better designed structure than the Hangar 9 ARF. It's design includes solid balsa sheet horizontal and vertical stabs as well as elevators and rudder. While the construction of the stabs on the Hangar 9 seem to be working in all but a few examples, such as the problem I had, I still believe it to be inadequate for an airframe of this type and size. It is interesting to note that the soon to be released larger Hangar 9 P-51 (77" span) does not have this kind of construction on the stabs. It has fully sheeted, airfoil shaped stabs. I believe the original Hangar 9 P-51 should have had similar.
Now, lest anyone get the wrong impression about this airframe, I want to make it clear that what you have when ready to fly this plane is one of the sweetest flying, no bad habits airplanes you could ever wish for. Mine is a little heavier than most at 11 lbs but this plane's performance and flying characteristics are not hampered at all because of the weight. Mine glides a phenomenal distance to an extremely light and slow touchdown. As a former pylon racer and current jet pilot, I tend to really wring mine out every time I fly it. Except for that initial flutter problem, it handles easily anything you can put it through.
05-15-2003, 12:50 AM
#4
Member
Join Date: Feb 2003
Location: ROCKWALL, TX,
Posts: 33
Likes: 0
Received 0 Likes
on
0 Posts
H9 P-51 Mods
WOW.....
Had no intention of hitting a nerve.... Just mentioned what I had read many-many months back.
-Mine did flutter on that one unlucky day though,,,,, Jumped into the air before I wanted it to, stalled, hit the ground,,,,,then fluttered,,,,,(along with my heart)
Smitty
Had no intention of hitting a nerve.... Just mentioned what I had read many-many months back.
-Mine did flutter on that one unlucky day though,,,,, Jumped into the air before I wanted it to, stalled, hit the ground,,,,,then fluttered,,,,,(along with my heart)
Smitty
