Top Flite Giant Scale Spitfire ARF
11-02-2014, 07:19 AM
#378
More progress, the cowling has been reworked to fit a bit better. As is, the gap between it and the fuse is not too attractive. I have also moved the radiator/oil cooler scoops out to the correct location. Well, as close to correct as I can get. Cannon blisters are essentially done and only need a light sanding before the base primer coat is applied. Going to start the process of glassing the fuse next.
Last edited by SpitfireMkII; 11-02-2014 at 07:23 AM.
11-06-2014, 02:28 AM
#379
Hi,
Could you explain what you mean by this? How would it make the problem worse if you were to open it up at the scale spot?
11-06-2014, 02:30 AM
#380
Hi,
I have one of these on the way. For those of you talented builders out there, how much trouble do you suppose it would be to put a teenie bit more dihedral in the wing? How would some of you do it if you were so inclined?
I have one of these on the way. For those of you talented builders out there, how much trouble do you suppose it would be to put a teenie bit more dihedral in the wing? How would some of you do it if you were so inclined?
11-06-2014, 05:47 AM
#381
IMO, opening just the front of the air scoop will direct high pressure air into the back side of the engine compartment and build essentially a bubble of air in there since there is no place for that air to exit. With cooling, the old rule of thumb goes, the outlet needs to be 4 times the size of the inlet. Opening around the engine and the scale scoop area creates lots of inlet area but no outlet area.
Leaving the front closed but opening the bottom of it as I have done, should allow the air that is coming at and through the cooling fins to flow through and easily exit behind the engine as the plane moves forward through the air, aiding in cooling. Not a very scientific explanation I know, but then we'd really need a wind tunnel or computer simulation to actually see the exact airflow and how it is being effected.
As for dihedral, where there is a will there is a way. Is having that visual dihedral all that important? My experience with dihedral is that too much can create a "wobble" in wind especially if the vertical fin sizing is off. My Yellow Spit wobbles quite a bit in the wind, perhaps that's what the TF engineers were trying to remove.
Leaving the front closed but opening the bottom of it as I have done, should allow the air that is coming at and through the cooling fins to flow through and easily exit behind the engine as the plane moves forward through the air, aiding in cooling. Not a very scientific explanation I know, but then we'd really need a wind tunnel or computer simulation to actually see the exact airflow and how it is being effected.
As for dihedral, where there is a will there is a way. Is having that visual dihedral all that important? My experience with dihedral is that too much can create a "wobble" in wind especially if the vertical fin sizing is off. My Yellow Spit wobbles quite a bit in the wind, perhaps that's what the TF engineers were trying to remove.
11-06-2014, 07:42 AM
#382
Hi,
Thank you. I understand now. I didn't last night at 3:30am on Percocet. Your Y/A Spit wobbles? Mine didn't, and I haven't seen it in the several others I've flown or seen videos of. I wonder what's causing it in yours. I doubt it's the dihedral.
Thank you. I understand now. I didn't last night at 3:30am on Percocet. Your Y/A Spit wobbles? Mine didn't, and I haven't seen it in the several others I've flown or seen videos of. I wonder what's causing it in yours. I doubt it's the dihedral.
11-06-2014, 09:11 AM
#384
Lifer, you know what I'm talking about, Corsairs are known for it especially.
There is nothing wrong with the Yellow Spit, no play in the rudder or anything like that. It flies great overall except when you get turbulent/gusty wind. It has to do with the amount of dihedral and the size of the vertical. I won't say the vertical is too small, because you may have too much dihedral, it goes either way. It is not clear if it could be defined as "Dutch Roll" but it is very similar.
Without going into a long story, I once flew a UAV that had so much dihedral and not enough tail that it was almost uncontrollable in wind, in fact in turns, if you weren't smooth, it would spin on you. Being a three channel plane (Rudder/Elv) we expected a little wobble in wind but this was ridiculous. In order to correct it, we had to make the vertical much larger to compensate for the amount of dihedral. I didn't support the more dihedral/more fin design but that would make the story too long.
TF designs some good flying airplanes, I'd be willing to bet that they went with less dihedral in order to keep the vertical a bit smaller and more scale like. If they kept the dihedral, everyone would be complaining that the vertical and rudder were too big, or that it doesn't fly well.
I also think the use of different airfoils between the root and tip (as TF does) can cause it to appear to have less dihedral.
Its all a compromise.
There is nothing wrong with the Yellow Spit, no play in the rudder or anything like that. It flies great overall except when you get turbulent/gusty wind. It has to do with the amount of dihedral and the size of the vertical. I won't say the vertical is too small, because you may have too much dihedral, it goes either way. It is not clear if it could be defined as "Dutch Roll" but it is very similar.
Without going into a long story, I once flew a UAV that had so much dihedral and not enough tail that it was almost uncontrollable in wind, in fact in turns, if you weren't smooth, it would spin on you. Being a three channel plane (Rudder/Elv) we expected a little wobble in wind but this was ridiculous. In order to correct it, we had to make the vertical much larger to compensate for the amount of dihedral. I didn't support the more dihedral/more fin design but that would make the story too long.
TF designs some good flying airplanes, I'd be willing to bet that they went with less dihedral in order to keep the vertical a bit smaller and more scale like. If they kept the dihedral, everyone would be complaining that the vertical and rudder were too big, or that it doesn't fly well.
I also think the use of different airfoils between the root and tip (as TF does) can cause it to appear to have less dihedral.
Its all a compromise.
Last edited by SpitfireMkII; 11-06-2014 at 09:18 AM.
11-06-2014, 09:58 AM
#385
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All of the 50 size Kyosho warbirds I owned have had yaw instability on a windy day, with the exception of the Zero.
The TF 40 giant scale I currently fly seems very stable in similar conditions, I had wondered if planes with flat tail surfaces are more prone to the 'waggle' as the Kyosho Zero has an air foiled verticle stabiliser and tracks very well. But I think there are a number of aspects of a design that combine to make a plane stable (or otherwise) in yaw on a windy day.
If it is windy at the flying field we get the PIper Cubs out and practice our rudder control
The TF 40 giant scale I currently fly seems very stable in similar conditions, I had wondered if planes with flat tail surfaces are more prone to the 'waggle' as the Kyosho Zero has an air foiled verticle stabiliser and tracks very well. But I think there are a number of aspects of a design that combine to make a plane stable (or otherwise) in yaw on a windy day.
If it is windy at the flying field we get the PIper Cubs out and practice our rudder control
11-06-2014, 10:13 AM
#386
Spit,
If I sounded defensive of the Y/A, that's not how I meant it. I know the waggle you mean. I see it in nearly every CARF warbird I've ever seen fly. I just didn't experience that with the Spit. I figured it was the fat wing that kept it stable. That waggle is different than the dutch roll (like what an A-4 does) and is plain when you have it. Looks like the bird is flying through turbulent air.
If I sounded defensive of the Y/A, that's not how I meant it. I know the waggle you mean. I see it in nearly every CARF warbird I've ever seen fly. I just didn't experience that with the Spit. I figured it was the fat wing that kept it stable. That waggle is different than the dutch roll (like what an A-4 does) and is plain when you have it. Looks like the bird is flying through turbulent air.
11-06-2014, 10:21 AM
#387
Hi,
But back to the TF, yeah, the flat angle does irritate me. When I read all the irritation with the inexplicably goofy shape of the TF GS Corsair rudder, I couldn't understand what the big deal was until I had one in my hand and thought, "Oh, no. That's definitely gotta go."
But back to the TF, yeah, the flat angle does irritate me. When I read all the irritation with the inexplicably goofy shape of the TF GS Corsair rudder, I couldn't understand what the big deal was until I had one in my hand and thought, "Oh, no. That's definitely gotta go."
11-06-2014, 10:53 AM
#388
Nope, didn't take it that way. Like I said, it's all a compromise. I love flying the Yellow and hope the TF flies as well. I was just pointing out why, perhaps, TF would reduce the dihedral. Hope you don't think I was criticizing the Yellow.
11-06-2014, 11:28 AM
#389
First you would have to make a dihedral gauge with the degree of dihedral you want the wing to have.Then you would have to make a new wing joiner to match the dihedral gauge angle.Then you would have to peel back the Monokote covering and the balsa sheeting from each wing half at the root rib.
Then remove the root rib from each wing half; reposition each root rib using the dihedral gauge to give each root rib the new degree of dihedral, and then secure the two root ribs with CA glue.
Then you would need to adjust the two holes in each root rib on each wing half to accept the two wing alignment dowels at the new dihedral angle. Then reposition the Monokote covering using a heating iron, now you are ready to epoxy the wing halves together.
Take note that changing the wing dihedral will change the stance of the landing gear. The landing gear will be splayed outward, similar to the stance of the ME-109, but not as much of a splay as the ME-109.
I have done this dihedral change on a TF Spitfire before. I changed the dihedral to 6 degrees, this change made the Spitfire look more scale and it flew more stable in flight ,especially during banking.
Roger
Last edited by ForcesR; 11-06-2014 at 11:50 AM. Reason: Word seperation
11-06-2014, 12:28 PM
#390
Roger, That's quite a bit of work there, far more than I'm willing to do! I'm pretty lazy these days when it comes to building
Can you elaborate as to how it flies better? Stable in what regard ?Do you have any photos of it? Curious to see how different it looks.
Thanks !
Can you elaborate as to how it flies better? Stable in what regard ?Do you have any photos of it? Curious to see how different it looks.
Thanks !
Last edited by SpitfireMkII; 11-06-2014 at 01:17 PM.
11-06-2014, 07:14 PM
#392
Roger, That's quite a bit of work there, far more than I'm willing to do! I'm pretty lazy these days when it comes to building
Can you elaborate as to how it flies better? Stable in what regard ?Do you have any photos of it? Curious to see how different it looks.
Thanks !
Can you elaborate as to how it flies better? Stable in what regard ?Do you have any photos of it? Curious to see how different it looks.
Thanks !
When i changed the wing dihedral from 4 to 6 degrees I found that in level flight the Spit felt and flew more stable with less minute aileron adjustments to maintain wing level flight. The most noticeable difference I found is making a banking turn, the Spit felt and looked more stable without any need for more or less aileron or elevator imput to execute and complete the turn. In my eyes and mind, the banking turns looked more professionally done, as if an expert were on the sticks, and I'm far from being an expert!
The first photo, grey camo Spitfire has 4 degree wing dihedral; the remaining photos show Spitfire wing with 6 degree dihedral.
Roger
Last edited by ForcesR; 11-06-2014 at 07:29 PM. Reason: Photo selection
11-07-2014, 03:11 AM
#393
Thanks Roger, appreciate it. TF seems to have a design formula they stick with, seems most of their offerings have less dihedral than their full size counterpart. It will be interesting to take both my Spits out for a comparison once the TF is done.
11-07-2014, 04:26 AM
#394
What is the make of the other Spitfire that you have? I have several myself, the TF 63" WS is way more stable in flight than my H9 65" WS Spitfire. I also have the new H9 30cc 81" WS Spit and the ESM 89" WS Spit; unfortunately I am a Spitfire nut Lol!!
Roger
11-07-2014, 05:26 AM
#395
Not sure I would agree with the landing gear thing since Robart makes gear for the Yellow Spit and their TF gear is labeled specifically for the TF ARF. I think the dihedral is a flight performance thing. Pattern and aerobatic planes fly very good overall, better than most trainers, especially in the wind. They don't have dihedral for the most part and dont usually have coupling issues like we see in scale warbirds.
I think TF is trying to achieve a good compromise of scale looks and good flight characteristics. I have the TF P-47 (For sale here on RCU) and have had the P-51, in addition to having flown their Corsair. They all fly solid and predictable, although the Corsair wobbles in the wind. Of course, if you take the dihedral out of the Corsair it no longer resembles a Corsair, so the compromise is in performance.
I have had several spits over the years but never liked the way they flew. Right now I have the Yellow MKXIV which I find awesome to fly. The take offs require lots of rudder but the landings are "money for old rope". I hate to admit to how easy it is for me to land it. I'm still working on getting the ailerons and rudder to my liking in flight, a matter of getting the expo, travel and differential to my preferences. I had a cylinder fail in one of the retracts the other day, combination of old o-rings, worn parts and cold weather. That's the first failure of retracts since my Ziroli P-40 ten years ago. So I had the priveledge of a belly landing. No major damage, small crack in the air scoop, all fixed and just waiting on the new cylinder. A testament to how easy the landings are.
I'm guilty of being a certified Spit nut as well. I've been to England three times now to hit museums and the air shows at Duxford. Almost passed out when they flew 21 examples at the same time in 2000!
I think TF is trying to achieve a good compromise of scale looks and good flight characteristics. I have the TF P-47 (For sale here on RCU) and have had the P-51, in addition to having flown their Corsair. They all fly solid and predictable, although the Corsair wobbles in the wind. Of course, if you take the dihedral out of the Corsair it no longer resembles a Corsair, so the compromise is in performance.
I have had several spits over the years but never liked the way they flew. Right now I have the Yellow MKXIV which I find awesome to fly. The take offs require lots of rudder but the landings are "money for old rope". I hate to admit to how easy it is for me to land it. I'm still working on getting the ailerons and rudder to my liking in flight, a matter of getting the expo, travel and differential to my preferences. I had a cylinder fail in one of the retracts the other day, combination of old o-rings, worn parts and cold weather. That's the first failure of retracts since my Ziroli P-40 ten years ago. So I had the priveledge of a belly landing. No major damage, small crack in the air scoop, all fixed and just waiting on the new cylinder. A testament to how easy the landings are.
I'm guilty of being a certified Spit nut as well. I've been to England three times now to hit museums and the air shows at Duxford. Almost passed out when they flew 21 examples at the same time in 2000!
Last edited by SpitfireMkII; 11-07-2014 at 06:11 AM.
11-07-2014, 06:30 AM
#396
SpitfireMKII; I would have loved to have been there too, to see 21 Spitfires and hear 21 Merlins fly overhead. Some folks are just so darn lucky to be in the right place at the right time!!
Speaking of Corsair tail waggle, every Corsair I seen in flight has the same trait, the "tail waggle". From my observations, it seems to only happen when the wind direction is at an angle to the nose and not straight on the nose. I asked the tail wag question to the pilot who flys a restored F4U Corsair for Vintage Wings of Canada, his response was, "it sure does". So if the FS Corsair tail wags too, then the majority of RC Corsairs fly scale, even my foam Corsair has the tail waggle.
I work for a Aerospace Engineering firm and I have had discussions numerous times with the engineers concerning wing dihedral. According to the engineers, wing dihedral adds to the stability of an aircraft, although if to much dihedral is given to a wing, then stability is compromised. Also the higher the dihedral, the lower the axis roll. An aircraft with zero wing dihedral will roll much quicker than the same aircraft with added wing dihedral. This explains why aerobatic aircraft have very little or no wing dihedral. A good example of this is the "Red Bull" pylon racers. Actually the engineers encouraged me to change the wing dihedral from 4 to 6 degree on my TF Spitfire; not only for the scale look but also for scale stability and manueveability in comparsion to the FS Spitfire. Now If I can get my hands on the new TF giant Spitfire, guess what I'll be doing Lol!
Roger
Speaking of Corsair tail waggle, every Corsair I seen in flight has the same trait, the "tail waggle". From my observations, it seems to only happen when the wind direction is at an angle to the nose and not straight on the nose. I asked the tail wag question to the pilot who flys a restored F4U Corsair for Vintage Wings of Canada, his response was, "it sure does". So if the FS Corsair tail wags too, then the majority of RC Corsairs fly scale, even my foam Corsair has the tail waggle.
I work for a Aerospace Engineering firm and I have had discussions numerous times with the engineers concerning wing dihedral. According to the engineers, wing dihedral adds to the stability of an aircraft, although if to much dihedral is given to a wing, then stability is compromised. Also the higher the dihedral, the lower the axis roll. An aircraft with zero wing dihedral will roll much quicker than the same aircraft with added wing dihedral. This explains why aerobatic aircraft have very little or no wing dihedral. A good example of this is the "Red Bull" pylon racers. Actually the engineers encouraged me to change the wing dihedral from 4 to 6 degree on my TF Spitfire; not only for the scale look but also for scale stability and manueveability in comparsion to the FS Spitfire. Now If I can get my hands on the new TF giant Spitfire, guess what I'll be doing Lol!
Roger
11-07-2014, 07:02 AM
#397
Changing the dihedral would be fairly easy. From the bottom of the dihedral brace, cut the brace going from 1/8th to zero at the center. Do this for both sides and then glue the cut pieces onto the top of the brace with epoxy. Good skills with a bandsaw would help here!
Get a piece of 1/8th hard balsa and trace around the rib profile as accurately as possible. Then, carefully block sand the rib pattern from 1/8th to zero bottom to top. Cut a relief opening for the brace to pass through. If the first one isn't darn near perfect, make another. It's only a piece of balsa. Trial fit the assembly and shim the dihedral brace with plywood or hard balsa and sand to a tight fit. Once satisfied, glue the entire assembly together with slo-set epoxy.
Add a strip of monokote on the exposed portion of the balsa shim on the bottom of the wing.
Buy some motor mount shims from Foremost Products and shim the appropriate corners of the retracts til they look right, tighten down the retract mounting bolts and test for operation.
Get a piece of 1/8th hard balsa and trace around the rib profile as accurately as possible. Then, carefully block sand the rib pattern from 1/8th to zero bottom to top. Cut a relief opening for the brace to pass through. If the first one isn't darn near perfect, make another. It's only a piece of balsa. Trial fit the assembly and shim the dihedral brace with plywood or hard balsa and sand to a tight fit. Once satisfied, glue the entire assembly together with slo-set epoxy.
Add a strip of monokote on the exposed portion of the balsa shim on the bottom of the wing.
Buy some motor mount shims from Foremost Products and shim the appropriate corners of the retracts til they look right, tighten down the retract mounting bolts and test for operation.
11-07-2014, 08:00 AM
#398
Lifer; that is an excellent idea! I would never have thought of doing it that way; it's a lot less work and less complicated than the way I would do the wing dihedral change. That's what I like about these forums, someone always comes up with an easier way to do things. I will use this method to change the wing dihedral when I get my hands on the TF giant Spitfire.
Roger.
Roger.