Official FlightLine RC 1600mm P-38 Lightning Thread

[FLTRI]

Apples to oranges, but...

I have an 800mm Corsair that requires up elevator to fly straight and level. If you go to Motion's site and look at the glamor shots of the plane, almost all of the pics show it flying with up elevator. We discussed this on the 800mm warbird thread, and the general consensus was the horizontal stabilizer is not in line with the thrust angle of the prop. Several folks modified their Corsairs by shaving the area where the H-stab fits, by basically lowering the front of the horizontal stabilizer a couple of millimeters. Then, they can fly straight and level with the elevator at true neutral. Basically, it was a design flaw (maybe?) that wasn't caught, and corrected at the factory.

Link to the Corsair here. http://www.motionrc.com/fms-f4u-cors...-wingspan-pnp/

Now, maybe the demo pilot was just holding up elevator when the all of the pictures were snapped, but it does seem odd that it's up in every picture. Also, it's about the same amount of up trim mine needs for straight and level flight.

Like I said, apples and oranges. Just throwing it out there...

Edit: I did try moving CG to the rear to get the elevator neutral on that plane. It didn't work, just made for an obviously tail heavy plane. e.g. uncontrollable...

[Arycon]

Hey...I remember reading something about the Aces of Iron 1/8th pilot being perfect scale for this P-38, despite the plane being 1/10th. Can anyone confirm? Im anxious to get one and paint it up since I used to paint minatures. Thanks.

[Aros]

I am anxious as well to get an Aces of Iron pilot in mine...I think Brandon has a 1/8 scale in his and it looks nearly identical in size to the stock pilot.

[Arycon]

I am anxious as well to get an Aces of Iron pilot in mine...I think Brandon has a 1/8 scale in his and it looks nearly identical in size to the stock pilot.

I hear ya. I wanna go ahead and order one to get cracking on painting it. Hey, Brandon, can you confirm 1/8th AoI?

[OV10]

Apples to oranges, but...

I have an 800mm Corsair that requires up elevator to fly straight and level. If you go to Motion's site and look at the glamor shots of the plane, almost all of the pics show it flying with up elevator. We discussed this on the 800mm warbird thread, and the general consensus was the horizontal stabilizer is not in line with the thrust angle of the prop. Several folks modified their Corsairs by shaving the area where the H-stab fits, by basically lowering the front of the horizontal stabilizer a couple of millimeters. Then, they can fly straight and level with the elevator at true neutral. Basically, it was a design flaw (maybe?) that wasn't caught, and corrected at the factory.

Link to the Corsair here. http://www.motionrc.com/fms-f4u-cors...-wingspan-pnp/

Now, maybe the demo pilot was just holding up elevator when the all of the pictures were snapped, but it does seem odd that it's up in every picture. Also, it's about the same amount of up trim mine needs for straight and level flight.

Like I said, apples and oranges. Just throwing it out there...

Edit: I did try moving CG to the rear to get the elevator neutral on that plane. It didn't work, just made for an obviously tail heavy plane. e.g. uncontrollable...

Hello Injected Roadglide,
Thanx for the Edit comment as well as the intro apples/oranges analogy. Based on what you said it is my strong suspicion that there is an incidence issue with the horizontal stab. It is not the first time I have heard or seen this occur. I had an incidence issue with my Dynam ME-262 whereas the horizontal stab required +5 degrees incidence because it was never designed correctly to account for the low hung EDF's thrust alignment or vise versa. Now I know I will have some work ahead of me when I do get this airframe in hand on the second round. This is unless of course FlightLine has corrected it on the next batch based upon all the observations documented about the abnormal offset required of the elevator in order to hold level flight.
This was the info I was looking for, appreciate ya just throwing it out there.

[FLTRI]

Hello Injected Roadglide,
Thanx for the Edit comment as well as the intro apples/oranges analogy. Based on what you said it is my strong suspicion that there is an incidence issue with the horizontal stab. It is not the first time I have heard or seen this occur. I had an incidence issue with my Dynam ME-262 whereas the horizontal stab required +5 degrees incidence because it was never designed correctly to account for the low hung EDF's thrust alignment or vise versa. Now I know I will have some work ahead of me when I do get this airframe in hand on the second round. This is unless of course FlightLine has corrected it on the next batch based upon all the observations documented about the abnormal offset required of the elevator in order to hold level flight.
This was the info I was looking for, appreciate ya just throwing it out there.

Thanks man, appreciate the appreciation. And technically, I should be FLTRU now. I sold the "I" last year, and upgraded to a wet Rushmore bike. Gawd, it's a great motorcycle...

Yeah, I think there's a design error in our P-38's. Neutral elevator should be neutral elevator, not 4mm up elevator. That said, 4mm up flies very well and it's barely up, compared to the throw that the big 17g elevator servo gives us. Should it be neutral? Yeah, I think it should. I also think the gator skin should be less. A lot less. A whole lot less. Am I disappointed in my Lightning? A little, yes I am. Would still buy it again knowing what I know now...

Hell yes.

[pmisuinas]

Painting still in work. Had other life requirements get in the way (like 20 cubic yards of mulch) but am making some progress. I agree with the overall sentiment that for the silver it is much harder to hide the gatoring.

Reference the 4mm up elevator being "neutral". The last several posts have hit on the cause--incorrect alignment of surfaces to thrust line. If all was correct, then there would not be any noticeable up trim for level flight --and it would not be speed dependent. Just something we will have to live with on this model, as off the top of my head, I can't think of anything that can be done to change it. Not going to be able to separate the stab and shim it, unless you want to really get into rebuilding. Adding up thrust would spoil the appearance by tilting the props so that it just wouldn't look right. Maybe changing the wing incidence is a possibility--might be able to shim it and fill in the space, but would then have to fair in the boom fronts. Way too much work...

Most reasonable response is just accept 4mm up trim is needed and go enjoy flying :-) Pete M

[OV10]

Reference the 4mm up elevator being "neutral". The last several posts have hit on the cause--incorrect alignment of surfaces to thrust line. If all was correct, then there would not be any noticeable up trim for level flight --and it would not be speed dependent. Just something we will have to live with on this model, as off the top of my head, I can't think of anything that can be done to change it.
Most reasonable response is just accept 4mm up trim is needed and go enjoy flying :-) Pete M

Hello Pete,
We don't just have to accept it, if FlightLine is going to be the "New Big Dog" over FMS this is where they show us what they are really made of and jump all over this deficiency that has been so notably documented by the consumer and just make it right. For those in the early round of ownership, yeah your thought to just accept the 4mm is the most reasonable for now. My personal desire as expressed in in my prior post#1665 is that it gets fixed in the next batch, no waiting for a ver 8 :dodgy:
Best regards,

[xviper]

My personal desire as expressed in in my prior post#1665 is that it gets fixed in the next batch, no waiting for a ver 8 :dodgy:
Best regards,

Since it's in the manual, I doubt they consider it something "broken" and needs to be fixed. If they did "fix" it, then all the manuals have to be revised. I can't fully explain why some planes just require some UP ELE but they do. Most of them seem to be of the twin tail boom variety. I'm sure there are conventional tail model planes that need UP as well but the twin boom type are easier to see that there is distinctly UP on the ELE.
A simple "fix" would be to re-design the mounting angle for the horizontal tail surface. Then we'd see a neutral ELE setting and nobody would know the wiser or even ask the question. Personally, I'm not concerned. This plane so well right side up, up side down and sideways.

[OV10]

Since it's in the manual, I doubt they consider it something "broken" and needs to be fixed.The manual notation was the method to correct for the design error If they did "fix" it, then all the manuals have to be revised. A simple addendum insert for the existing printed manuals I can't fully explain why some planes just require some UP ELE but they do. I can explain it, incorrect incidence Most of them seem to be of the twin tail boom variety. What examples of most? The 1450 FMS as far as I 'm aware didn't. My Bronco doesn't I'm sure there are conventional tail model planes that need UP as well but the twin boom type are easier to see that there is distinctly UP on the ELE.I can't disagree as I mentioned earlier in a prior post that my Dynan ME-262 needed a +5 positive incidence stab mod due to down elevator needs because of incorrect thrust/stab incidence which is due to incorrect designs.
A simple "fix" would be to re-design the mounting angle for the horizontal tail surface. Then we'd see a neutral ELE setting and nobody would know the wiser or even ask the question. Right On, add a couple degrees negative stab incidencePersonally, I'm not concerned. This plane so well right side up, up side down and sideways.

Hello Viper, please don't take the above injected underlined comments as trying to be combative because I am not. Am just trying to point out that we as consumers don't need to accept complacency or inadequacy from the new guy and should expect them to make it right versus making rationalizations for the shortfall. I am really glad to see FlightLine as a challenger to the FMS school of thought on acceptable pricing and giving the consumer a model that has been clamored for a while but that old school of just accept it and wait for version whatever doesn't need to be.
Best regards,

[Aros]

As an ever-learning student of aerodynamics, it seems this is all a matter concerning the incidence of the H stab, correct? If either the wing or H stab was re-molded to have a different angle of incidence, this could remove the need for the 4mm up for neutral? I wonder then where the existing mold is at in relation to the full scale? Anyone know?

[pmisuinas]

Hello Pete,
We don't just have to accept it, if FlightLine is going to be the "New Big Dog" over FMS this is where they show us what they are really made of and jump all over this deficiency that has been so notably documented by the consumer and just make it right. For those in the early round of ownership, yeah your thought to just accept the 4mm is the most reasonable for now. My personal desire as expressed in in my prior post#1665 is that it gets fixed in the next batch, no waiting for a ver 8 :dodgy:
Best regards,

I agree with the sentiment, depending on cost/effort, it would be nice to see changes in later production runs. My comments are aimed at what one can do now with the existing model. Changing it for later would require modifying the boom molds, I expect the math could translate 4mm up into the needed stab incidence change. it would indeed be nice to see vX take care of this...Pete M

[rtwatkins]

As an ever-learning student of aerodynamics, it seems this is all a matter concerning the incidence of the H stab, correct? If either the wing or H stab was re-molded to have a different angle of incidence, this could remove the need for the 4mm up for neutral? I wonder then where the existing mold is at in relation to the full scale? Anyone know?

Not sure if this would help, but here's some of the Lockheed plans for the P-38L. (seems legit, might need some checking though)


Seems the full scale plane had neutral.

Also, the full scale had fowler split flaps... ;)

[MikeT]

Hello Pete,
We don't just have to accept it, if FlightLine is going to be the "New Big Dog" over FMS this is where they show us what they are really made of and jump all over this deficiency that has been so notably documented by the consumer and just make it right. For those in the early round of ownership, yeah your thought to just accept the 4mm is the most reasonable for now. My personal desire as expressed in in my prior post#1665 is that it gets fixed in the next batch, no waiting for a ver 8 :dodgy:
Best regards,

God this sounds just like the FMS crowd over at the other forum. Do you own one of these?

Mike

[PlaneCrazy]

God this sounds just like the FMS crowd over at the other forum. Do you own one of these?

Mike

+1 +1 +1+1+1

[Arycon]

No offense, but if you want perfection, go balsa and build it yourself. This isnt meant to be an impecable model P-38. Not for this price point. Seriously...I dont hear anyone griping about fowler flaps. Numerous reports that the plane flies stable right side up and inverted with zero issues. Would it be nice of them to address it and fix.it soon? Yep. Will they? Dont know. Im flying the crap out of mine regardless.

Truly. No offense intended, but for the price point we got a lot out of this model. Balsa is the only way to get true perfection and scale accuracy...but yeah...one engine would cost you what this plane did.

You get what you pay for. In this instance I say that as a compliment. It isnt like FMS hasnt had its share of issues. V8 P-51...yeah, cause motor mounts break loose and props disengage in mid flight.

No plane is flawless. Not even the real P-38. For now, enjoy it and fly and hopefully Flightline will bend their ear to us and make adjustments as needed in future batches. And please...please be civil, guys. This isnt that other RC Forum afterall.

Side note: Callie Graphics and AOI pilot ordered! P-38 should be solid for next week. Yeah-yuh!

[Shirty]

As an ever-learning student of aerodynamics, it seems this is all a matter concerning the incidence of the H stab, correct? If either the wing or H stab was re-molded to have a different angle of incidence, this could remove the need for the 4mm up for neutral? I wonder then where the existing mold is at in relation to the full scale? Anyone know?

Yes. As the boys have noted, incidence being incorrect could cause the need for up elevator, and also why changing battery position may have little effect. Yes, the real one did not need up elevator to fly straight. Incidence is something I always check before installing a horizontal stab in a balsa plane, as most large 3D balsa models require you to cut and sand the wood, prior to installing the stab and gluing/epoxy in place. There's a good meter I use from hangar 9, that will digitally measure the incidence and I always use it in these large balsa builds to make sure I have the incidence correct, prior to permanently fixing the stab in place.

Usually if incidence is out, you will need to trim to fly straight and you get other side effects as noted before, such as the negative effect of up trim inverted. I posted a while ago when one of the first flight videos came out that motion did, that the p38 seemed to need a lot of down elevator to fly inverted, and in the vid the plane is flying in a high alpha condition inverted. I guess we know why now. I'll check this with my incidence meter when I get my p38.

All this is manageable, it just means that rolls will be a tiny bit corkscrewy due to the up elevator, and inverted flight will require the pilot be to pushing quite a bit of down elevator on their sticks to hold it straight, to combat the up trim added for normal upright level flight, and the nose heavy condition the incidence induces. If you check one of motions first p38 vids, you can see in the low inverted passes the plane is very much in a high alpha condition inverted.

The fix with balsa is sanding or having to fill areas of the stab hole, until the incidence is correct with the wings. I personally don't think it's worth it in a foamy, and getting it exact with the size of the foam cells and compression etc I'd imagine would be pretty difficult.

I can live with having the p38 needing trim to combat the incorrect alignment of the stab, again as noted it's only 4mm and just means your plane won't track entirely straight, rolls will be a bit corkscrewy, and the pilot needs to be on his game inverted. Be careful if you fly inverted that the plane doesn't go too high into a high alpha condition, as the flow of air across the wings (especially the wingtips), will cause it to tip stall very quickly if you fly too slow inverted. Anybody familiar with inverted harriers in 3D flying will know about this, but if your wings start to rock when you are flying inverted, add power as you are approaching tip stall. Hope this helps.

Cheers boys.

[Shirty]

Here's a couple of pics showing the stab on my 74 inch edge. You can see I had to add a tiny sliver of wood on the top surface, to allow the stab to sit at the correct angle so the incidence is zero. :)

[OV10]

God this sounds just like the FMS crowd over at the other forum. Do you own one of these?

Mike

Hello MikeT,
Actually I am not a FMS fan because of their recent grab this past year of pricing greed and inability to move the market in a direction as asked for by the customer base. And yes I do own a FlightLine product and actually have contributed in great detail on both a build and flight review of it on this forum that many have appreciated. The other forum that you elude to I left behind in the dust 3 years ago when I found the Squawk. I hope that I've answered your questions satisfactorily.
Best regards,

[xviper]

Hello MikeT,
Actually I am not a FMS fan because of their recent grab this past year of pricing greed and inability to move the market in a direction as asked for by the customer base. And yes I do own a FlightLine product and actually have contributed in great detail on both a build and flight review of it on this forum that many have appreciated. The other forum that you elude to I left behind in the dust 3 years ago when I found the Squawk. I hope that I've answered your questions satisfactorily.
Best regards,

Charlie, kudos for such a well written and very dignified response. Unlike some of those on the "other" forum, the response could have been vile and repugnant. You rose above all that. :cool: