"USEFUL" Telemaster 40 mods?
05-08-2009 | 06:42 PM
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From: Mesa,
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"USEFUL" Telemaster 40 mods?
I built a Telemaster 40 back in the early 80's dead stock with an OS 40. Loved the plane! Traded it off for a small block Chevy intake manifold. [X(] I finally caved in and bought another kit and it arrived last night. I already have a few mods planned. One will be a bolt on wing. It will also most likely end up a twin electric mainly because I have two of everything to power it well as a twin but I don't have a single motor in the needed range. Either they're too big or too small. [&o] This kit is also the newer one that is taildragger with God awful heavy aluminum main gear. That gear is going in the trash and I'll build my own mains from wire and go trike gear. (I just prefer trike) I have an early set of plans too so I have all the bend angles for the gear. Plenty of silver solder too.
In doing some research on the plane I've seen a few posts regarding the incidence angles of the wing and the H-stab. The wing being at 3 degrees + and the stab at 1 degree +. Guys have said they were going to remove the positive incidence but none of them ever posted back with how the plane flew! Maybe it didn't.
I don't like a lot of incidence because I hate having to keep trimming for throttle changes. I realize it's a trainer but I'd still like to throw it around once in a while. Just mild aerobatics. Nothing wild. It's been almost 30 years since my first one and I honestly don't remember if I had to do a lot of trimming in flight. I'd love to hear from anyone that has changed the incidence. I don't care in the least about aerodynamic theories. I want to hear real world experiences.
I've also seen some posts about building slab or stick built flat H-stabs rather than the built up version. Once again nobody reports their findings back to the thread! I'd like to hear comments about this one as well.
I haven't even started the build yet. I've been trying to come up with a motor nacelle that I'm happy with first. I want something with some sexy curves like a C-130 but I'm not ending up with what I want. I've done six already and I'm using up a lot of balsa/ply so will probably cave in and just go with an ugly but easy to build boxy nacelle.
Joe
In doing some research on the plane I've seen a few posts regarding the incidence angles of the wing and the H-stab. The wing being at 3 degrees + and the stab at 1 degree +. Guys have said they were going to remove the positive incidence but none of them ever posted back with how the plane flew! Maybe it didn't.
I don't like a lot of incidence because I hate having to keep trimming for throttle changes. I realize it's a trainer but I'd still like to throw it around once in a while. Just mild aerobatics. Nothing wild. It's been almost 30 years since my first one and I honestly don't remember if I had to do a lot of trimming in flight. I'd love to hear from anyone that has changed the incidence. I don't care in the least about aerodynamic theories. I want to hear real world experiences. I've also seen some posts about building slab or stick built flat H-stabs rather than the built up version. Once again nobody reports their findings back to the thread!
I'd like to hear comments about this one as well. I haven't even started the build yet. I've been trying to come up with a motor nacelle that I'm happy with first. I want something with some sexy curves like a C-130 but I'm not ending up with what I want. I've done six already and I'm using up a lot of balsa/ply so will probably cave in and just go with an ugly but easy to build boxy nacelle.
Joe
05-08-2009 | 07:38 PM
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RE: "USEFUL" Telemaster 40 mods?
Joe, it's just one of those planes that doesn't need any mods. I did change the wing to bolt on but other then that ?????????? The new LG looks pretty good with holes drilled in it to lighten it up. Maybe some wheel pants?? It's just a perfect plane as designed.[8D]
05-11-2009 | 05:07 PM
#3
RE: "USEFUL" Telemaster 40 mods?
one mod i did was to change the way the fuse is built, just too tender as designed. built one up using 1/4 spruce sticks, now will take on anything!!! i did keep all incidences as designed and i went taildragger
05-11-2009 | 07:12 PM
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From: El Dorado, CA
RE: "USEFUL" Telemaster 40 mods?
ORIGINAL: turbojoe
I built a Telemaster 40 back in the early 80's dead stock with an OS 40. Loved the plane! Traded it off for a small block Chevy intake manifold. [X(] I finally caved in and bought another kit and it arrived last night. I already have a few mods planned. One will be a bolt on wing. It will also most likely end up a twin electric mainly because I have two of everything to power it well as a twin but I don't have a single motor in the needed range. Either they're too big or too small. [&o] This kit is also the newer one that is taildragger with God awful heavy aluminum main gear. That gear is going in the trash and I'll build my own mains from wire and go trike gear. (I just prefer trike) I have an early set of plans too so I have all the bend angles for the gear. Plenty of silver solder too.
In doing some research on the plane I've seen a few posts regarding the incidence angles of the wing and the H-stab. The wing being at 3 degrees + and the stab at 1 degree +. Guys have said they were going to remove the positive incidence but none of them ever posted back with how the plane flew! Maybe it didn't. I don't like a lot of incidence because I hate having to keep trimming for throttle changes. I realize it's a trainer but I'd still like to throw it around once in a while. Just mild aerobatics. Nothing wild. It's been almost 30 years since my first one and I honestly don't remember if I had to do a lot of trimming in flight. I'd love to hear from anyone that has changed the incidence. I don't care in the least about aerodynamic theories. I want to hear real world experiences.
I've also seen some posts about building slab or stick built flat H-stabs rather than the built up version. Once again nobody reports their findings back to the thread! I'd like to hear comments about this one as well.
I haven't even started the build yet. I've been trying to come up with a motor nacelle that I'm happy with first. I want something with some sexy curves like a C-130 but I'm not ending up with what I want. I've done six already and I'm using up a lot of balsa/ply so will probably cave in and just go with an ugly but easy to build boxy nacelle.
Joe
I built a Telemaster 40 back in the early 80's dead stock with an OS 40. Loved the plane! Traded it off for a small block Chevy intake manifold. [X(] I finally caved in and bought another kit and it arrived last night. I already have a few mods planned. One will be a bolt on wing. It will also most likely end up a twin electric mainly because I have two of everything to power it well as a twin but I don't have a single motor in the needed range. Either they're too big or too small. [&o] This kit is also the newer one that is taildragger with God awful heavy aluminum main gear. That gear is going in the trash and I'll build my own mains from wire and go trike gear. (I just prefer trike) I have an early set of plans too so I have all the bend angles for the gear. Plenty of silver solder too.
In doing some research on the plane I've seen a few posts regarding the incidence angles of the wing and the H-stab. The wing being at 3 degrees + and the stab at 1 degree +. Guys have said they were going to remove the positive incidence but none of them ever posted back with how the plane flew! Maybe it didn't.
I don't like a lot of incidence because I hate having to keep trimming for throttle changes. I realize it's a trainer but I'd still like to throw it around once in a while. Just mild aerobatics. Nothing wild. It's been almost 30 years since my first one and I honestly don't remember if I had to do a lot of trimming in flight. I'd love to hear from anyone that has changed the incidence. I don't care in the least about aerodynamic theories. I want to hear real world experiences. I've also seen some posts about building slab or stick built flat H-stabs rather than the built up version. Once again nobody reports their findings back to the thread!
I'd like to hear comments about this one as well. I haven't even started the build yet. I've been trying to come up with a motor nacelle that I'm happy with first. I want something with some sexy curves like a C-130 but I'm not ending up with what I want. I've done six already and I'm using up a lot of balsa/ply so will probably cave in and just go with an ugly but easy to build boxy nacelle.
Joe
I am presently building a Telemaster40 (picts attached). Once again I cut the dihedral in half and I will be installing the flaps. The standard boxy fuselage is getting a major overhaul this time.
Regards
05-15-2009 | 11:50 AM
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From: Mesa,
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RE: "USEFUL" Telemaster 40 mods?
Thanks guys. I've been looking at all the online forums lately and it looks like I should probably just leave the incidence alone. A bolt on wing is definite though. I just have to decide which method to use or maybe even come up with one of my own. Glow power is out of the question. It'll be electric for sure. I went ahead and built the firewall/motor box last night as well as mounting up the nose gear because I prefer trike gear. I also cut all the cooling holes in the firewall. The firewall is ready to accept a motor but I don't have one that isn't too small or too big for the application. I do have everything to make it a twin though so I plan to go that route. I simply can't come up with nacelles that I'm happy with.
I've only just started on the fuse and am taking my own sweet time as I have dozens of other planes to fly in the mean time. This isn't a rush build. I'd really like to take the time to do the twin motor mod right though. The nacelles are what are keeping me from getting really excited with this particular build. I have a bunch of late 60's-early 70's design twin plans but those nacelles are almost all carved from balsa blocks. That ain't gonna happen! I really like the look of C-130 nacelles ( I was a jet-mech on C-130's in the Navy). I have some plans for an "A" model C-130 but they suck beyond belief. If anyone has nacelle plans that they are willing to post up that are well designed and relatively easy to build I'd be forever grateful. Modifying them to work with this particular wing is not an issue. That's the easy part.
Joe
I've only just started on the fuse and am taking my own sweet time as I have dozens of other planes to fly in the mean time. This isn't a rush build. I'd really like to take the time to do the twin motor mod right though. The nacelles are what are keeping me from getting really excited with this particular build. I have a bunch of late 60's-early 70's design twin plans but those nacelles are almost all carved from balsa blocks. That ain't gonna happen! I really like the look of C-130 nacelles ( I was a jet-mech on C-130's in the Navy). I have some plans for an "A" model C-130 but they suck beyond belief. If anyone has nacelle plans that they are willing to post up that are well designed and relatively easy to build I'd be forever grateful. Modifying them to work with this particular wing is not an issue. That's the easy part.
Joe
05-18-2009 | 12:58 AM
#6
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RE: RE:
Andy Lennon did a bunch of aerodynamic study on the Sr Telemaster. One thing was found is that reduced dihedral and open wire landing gear were a catastrophe when it comes to going flat and being unrecoverable in a spin. His recomendation was to cover between the wires on each side of the Sr Telemaster gear and to leave the dihedral alone. With a rearward lateral center of area, spin recovery is difficult.
Original: pjwright
Okay I followed Lennon's procedure to calculate the lateral (spiral) stability of a model design. I was skeptical, because it sounded so low-tech ... but it appears to work. You find the "center of lateral area" (CLA) of a model using a 100% profile that is suspended from 2 or 3 different points, and run a plumb line down the length of the model each time. Where the lines intersect is the CLA. See Chapter 9 of 'Basics of R/C Model Aircraft Design' for the procedure.
What I found for the Sr Telemaster (ARF) suggested that reducing dihedral and/or adding to the vertical tail area quickly increased spiral instability. One of the posters on the mod thread complained that his plane was hard to get out of a flat spin ... dunno if these conditions are related.
Lennon says you have "neutral spiral stability" when the CLA is at 28% of the vertical tail moment arm (see diagram). My test suggests the factory Telemaster's CLA is nearly 30% of VTMA ... making it mildly susceptible to entering a spiral. When I took out dihedral (as a number of folks have done) on the mock-up, the spiral stability margin increased dramatically - to 37% ... well into the "very spirally unstable" zone in Lennon's estimation.
My intended mods include filling in the space between the LG wires (like a Cub), which improves the CLA location; and adding about 20 sq.in. to the rudder, which degrades it. I'm looking at a spiral stability margin of 32% ... still in the "mild" zone ... and I'll leave the dihedral alone.
Having gone through this exercise ... I wouldn't take these numbers to the bank, but the principle is what's important: if you move the CLA too far aft (even with the model balanced), there may be unintended consequences.
[img]{akamaiimageforum}/image/s4.gif[/img]
PJ
Okay I followed Lennon's procedure to calculate the lateral (spiral) stability of a model design. I was skeptical, because it sounded so low-tech ... but it appears to work. You find the "center of lateral area" (CLA) of a model using a 100% profile that is suspended from 2 or 3 different points, and run a plumb line down the length of the model each time. Where the lines intersect is the CLA. See Chapter 9 of 'Basics of R/C Model Aircraft Design' for the procedure.
What I found for the Sr Telemaster (ARF) suggested that reducing dihedral and/or adding to the vertical tail area quickly increased spiral instability. One of the posters on the mod thread complained that his plane was hard to get out of a flat spin ... dunno if these conditions are related.
Lennon says you have "neutral spiral stability" when the CLA is at 28% of the vertical tail moment arm (see diagram). My test suggests the factory Telemaster's CLA is nearly 30% of VTMA ... making it mildly susceptible to entering a spiral. When I took out dihedral (as a number of folks have done) on the mock-up, the spiral stability margin increased dramatically - to 37% ... well into the "very spirally unstable" zone in Lennon's estimation.
My intended mods include filling in the space between the LG wires (like a Cub), which improves the CLA location; and adding about 20 sq.in. to the rudder, which degrades it. I'm looking at a spiral stability margin of 32% ... still in the "mild" zone ... and I'll leave the dihedral alone.
Having gone through this exercise ... I wouldn't take these numbers to the bank, but the principle is what's important: if you move the CLA too far aft (even with the model balanced), there may be unintended consequences.
[img]{akamaiimageforum}/image/s4.gif[/img]
PJ
05-18-2009 | 09:31 AM
#7
Senior Member
RE:
I have built and flown several of these. All converted to tail draggers, bolt on wings and flat wings. The flat wing spins and recovers just fine. The flat wing (no dihedral) also rolls better. I did enlarge the rudder (doubled the size with about 10% of the area ahead of the hinge line) on the last two and that was also a nice improvement for increasing manuverability.
