Hello! Explorer build

[Headbang]

How does the build process go with gorilla glue vs hot glue? How long does it take to set?

Key to using gorilla glue is to make sure you have tape, rubber bands and various heavy objects handy to hold the parts in place ahead of time. Using white gorilla it take 30mins to an hour to setup. I tend to do all the parts I can at once, then walk away for a few hours. Another thing I have learned is the value of making pin pricks in places where you want strength, it gives the glue a place to expand into to, creating almost a glue nail. Biggest advantages are weight and sanding, you can really clean things up with some 240grit sand paper and make a pretty plane.

I think we have all hit the throttle on the bench with the prop on. I did it with an 19x8 prop once on a DM4330-435 6S, it ate a castle programming cable, my shirt, and the tail of another plane. Unfortunatly over the years I have managed to rack up a lot of scars on my hands from props, and been where you are a few times as well. All while tuning or testing.

 

[rmzalbar]

I managed to beat the hell out of the Fokker today. It's fun, but a heck of a lot harder to fly than my Explorer. My first time up it was extremely squirrelly, did an immediate tailstand and backflip onto its snout on takeoff.

OK, fine, so I add some lead to the nose and dial my expo up to 40. Flies now, except landing is nearly impossible. It has practically no tail authority while dead-stick, guess it really needs that prop wash, and nose-heavy, well, it will just dive right into the ground even with full back elevator at what would seem to be a reasonable landing speed. And if you do get the wheels on the ground, it just does a faceplant.

Also, holy crap, that newer F power pack is a beast. I replaced the 12A ESC with an Arris Swift 20A ESC after reading the actual specs for the RS2205, and, jeez, you just set it on the ground, pull the elevator back and rocket straight up into the sky. The three undercambered wings on this plane mean that pushing the throttle past mid-stick adds nothing to the performance except depleting your battery faster.

Great, well I have some practice now, so I can remove most of the weight and make it more neutral. Still not quite neutral, and still wants to ker-plop with the power off, but I manage a couple of not-too-high-speed landings into my driveway, still flipping forward onto its nose nearly every time. Oh, and the undercarriage is completely exploded with each bellyflop.

So it's back to the workbench for this one. The undercarriage needs to be totally redesigned to be strong, and with the wheels a bit further forward. The CG needs to be very carefully set. Some foam needs to be replaced, the wing corners need to be de-dented, and I should probably reinforce the wing struts before they fail now that I know how much this things loves splat landings. I'm glad I didn't spend a lot of time painting it. Best to get it predictable first.

 

[rmzalbar]

I think we have all hit the throttle on the bench with the prop on. I did it with an 19x8 prop once on a DM4330-435 6S, it ate a castle programming cable, my shirt, and the tail of another plane. Unfortunatly over the years I have managed to rack up a lot of scars on my hands from props, and been where you are a few times as well. All while tuning or testing.

I just looked up that motor. 2700 watts! An 18-inch prop? That thing could have crippled you if it touched flesh. One time I was cleaning my motorcycle chain on the centerstand, and I managed to feed my thumb into the rear sprocket. The big "props off" rule in that situation was to only turn the wheel backwards, and only by hand. Some people thought it was a clever idea to idle the motor while wiping lubricant on with a rag.. and.. yeah. It's a good thing I was only rotating my wheel by hand, albeit the wrong direction. The inertia totally crushed my thumb into a hamburger. Took a long time for it to sort itself out, but it did.

 

[d8veh]

I see too many people on this forum (normally beginners) judging theie planes to be nose or tail heavy from the way it flies. You should judge that by checking where the C of G is not by how agile it is. If the G-spot is correct, adding lead to the nose is not going to make the plane fly well. It'll fly and be less responsive, but you can get other trim problems and it'll make the plane fly faster and get more damage when it crashes. Instead, you should reduce the amount of movement on your control surfaces to calm the plane down.

As a general rule, the G-spot should be 25% to 33% back from the leading edge of a parallel wing. It's slightly more complicated if your wing is tapered or swept back, in which case you have to look at where the average wing is. You shouldn't let your G-spot move out of that range unless you know what you're doing and why you want it like that.

On a triplane, I'd want the Cof G closer to the 25% than the 33%, but FT give the correct position in their build video and theirs seems to fly well, so that would be where I'd have it.

 

[Hai-Lee]

I see too many people on this forum (normally beginners) judging theie planes to be nose or tail heavy from the way it flies. You should judge that by checking where the C of G is not by how agile it is. If the G-spot is correct, adding lead to the nose is not going to make the plane fly well. It'll fly and be less responsive, but you can get other trim problems and it'll make the plane fly faster and get more damage when it crashes. Instead, you should reduce the amount of movement on your control surfaces to calm the plane down.

As a general rule, the G-spot should be 25% to 33% back from the leading edge of a parallel wing. It's slightly more complicated if your wing is tapered or swept back, in which case you have to look at where the average wing is. You shouldn't let your G-spot move out of that range unless you know what you're doing and why you want it like that.

On a triplane, I'd want the Cof G closer to the 25% than the 33%, but FT give the correct position in their build video and theirs seems to fly well, so that would be where I'd have it.

Nice info but!

As the plane designs here require manual skills for wing profile accuracy the wing profiles can vary quite considerably and hence the exact location of the exact CG or balance point.

Add to that the simple fact that a lot of the designs have a ZERO incidence angle it is easy to have a plane built that is actually well balanced if only the wing profile was accurate to the original design. As for wing incidence it is known that too low a wing incidence angle will give the flight attitude as if the plane was tail heavy. It requires the wing incidence angle for lift and the only way to get this angle in flight is to fly nose UP!

Another thing to consider is that motors of the same part number description from different manufacturers can vary in weight as can even the batteries we use and the internal arrangement of the electrics can vary from builder to builder.

A final point to consider is that not everyone has access to the same quality of foamboard or even the same density. With varying material densities, Builder skills. and low wing incidence angles it can be a maze of confusing symptoms through which a person wishing to help must navigate!

Just a few things to consider!

Have fun!

 

[d8veh]

Nice info but!

As the plane designs here require manual skills for wing profile accuracy the wing profiles can vary quite considerably and hence the exact location of the exact CG or balance point.

Add to that the simple fact that a lot of the designs have a ZERO incidence angle it is easy to have a plane built that is actually well balanced if only the wing profile was accurate to the original design. As for wing incidence it is known that too low a wing incidence angle will give the flight attitude as if the plane was tail heavy. It requires the wing incidence angle for lift and the only way to get this angle in flight is to fly nose UP!

Another thing to consider is that motors of the same part number description from different manufacturers can vary in weight as can even the batteries we use and the internal arrangement of the electrics can vary from builder to builder.

A final point to consider is that not everyone has access to the same quality of foamboard or even the same density. With varying material densities, Builder skills. and low wing incidence angles it can be a maze of confusing symptoms through which a person wishing to help must navigate!

I'm not sure i understand what you're saying about the G-spot and I don't get what your saying about wing incidence either. I'm not saying I disagree with anything you wrote. I'm just not getting the point. Maybe my recent anaesthetic has messed up my comprehension.

To clarify what I mean, I'll reiterate what I wrote. Please let us know if you think I'm wrong.

it's fundamental that the G-spot needs to be in the right place. If it's not, then weight needs to be adjusted to make it so. Adding weight to make the G-spot wrong to compensate for a wrong incidence angle, bent tail or twisted wing is IMHO completely the wrong thing to do.

What I'm saying is that your first step should be to get the G-spot in the specified position or range. If it doesn't fly like that, it's because something else is wrong. You can see from the FT videos that all the FT planes fly nicely if you make them with the incidence and G-spot as specified; however, I add the caveat that it could be different if the pilot was no so experienced.

Having said that, I do see some problems with them that would affect newbs. They try to use swappable motor pods that have no down-thrust nor side-thrust. IMHO that's wrong for many of the planes. As a starting point for any plane that has a high wing, I'd use at least 2 deg of down-thrust and 2 deg of side-thrust. That would be a minimum for me on any of the beginners planes. High-wing planes just don't work very well without down-thrust. Increasing the wing incidence and bodging the G-spot is not going to make it fly well.

I've designed and flown many planes with zero wing incidence. That's pretty normal for an aerobatic plane. For such a plane, I always start with the G-spot at approximately 33% for a maiden flight, then start shifting it back as far as I dare to get the crazy flying characteristics that I like, but that's not for beginners.

 

[Hai-Lee]

I'm not sure i understand what you're saying about the G-spot and I don't get what your saying about wing incidence either. I'm not saying I disagree with anything you wrote. I'm just not getting the point. Maybe my recent anaesthetic has messed up my comprehension.

To clarify what I mean, I'll reiterate what I wrote. Please let us know if you think I'm wrong.

it's fundamental that the G-spot needs to be in the right place. If it's not, then weight needs to be adjusted to make it so. Adding weight to make the G-spot wrong to compensate for a wrong incidence angle, bent tail or twisted wing is IMHO completely the wrong thing to do.

What I'm saying is that your first step should be to get the G-spot in the specified position or range. If it doesn't fly like that, it's because something else is wrong. You can see from the FT videos that all the FT planes fly nicely if you make them with the incidence and G-spot as specified; however, I add the caveat that it could be different if the pilot was no so experienced.

Having said that, I do see some problems with them that would affect newbs. They try to use swappable motor pods that have no down-thrust nor side-thrust. IMHO that's wrong for many of the planes. As a starting point for any plane that has a high wing, I'd use at least 2 deg of down-thrust and 2 deg of side-thrust. That would be a minimum for me on any of the beginners planes. High-wing planes just don't work very well without down-thrust. Increasing the wing incidence and bodging the G-spot is not going to make it fly well.

I've designed and flown many planes with zero wing incidence. That's pretty normal for an aerobatic plane. For such a plane, I always start with the G-spot at approximately 33% for a maiden flight, then start shifting it back as far as I dare to get the crazy flying characteristics that I like, but that's not for beginners.

We are not in total disagreement but approaching the same question from different angles or directions.

If the models with which persons were having difficulty were retail offerings or laser cut balsa kits then following the plans or instructions for the indicated or recommended balance point is vital and a great predictor of flight performance but here the builds vary considerably.

As you would be aware the wing profile can vary the maximum lift point WRT to wing cord. Wings such as a simple plank, laminar flow and even super critical all have a different point on the cord which is used as a balance point.

In addition a wings incidence angle effects its actual performance. In order to support a certain weight there is a relationship between AoA and airspeed. If a wing has an incidence angle or AoA insufficient to generate or maintain sufficient lift the plane will not be able to fly without actually increasing its AoA. This increased angle in flight is often mistaken as a sign of being tail heavy,

There are a plethora of posts of persons who have set the CG correctly and the plane still flies, "Like it is tail heavy". My initial post was to try to broaden your response to include advice about things that could be actually considered as either design or build faults.

Of course when referring to incidence angles I am referring to the angles of the wing WRT to angle of the tail surfaces, both of which can be the subject of a build or design mistake.

Just telling persons that if they get the CG correct then the fault must be with either their ability, to measure the balance point, to set up their transmitter, or to even fly is not only wrong but also somewhat discouraging. As the forum users build in a wide variety of materials and densities then the weights of the resultant planes also vary considerably. For a set wing profile at a set speed to be able to support a greater weight is AoA must be increased. The simplest method is to increase the wings incidence angle.

When the FT Simple Cub was released there followed a storm of queries as to how to get the plane to fly properly. Much was made of setting the CG correctly but no real solution was offered. Not being my favorite type of plane a refrained from the build until some were becoming rather frantic about their inability to get it flying properly. I built one out of the heavier grade FB common here and tried to emulate the described issues. After eliminating a few "Gotchas" with the build I set about taming the beast and soon found that simply adjusting the wing incidence angle turned a squirrelly and unstable beast into a pussy cat. I revisited a few earlier design s and found the same response was applicable. Heck it even made the Explorer a real floater!

With your RC history I assume that you have flown both extremely nose heavy but also extremely tail heavy planes successfully. If you want a REAL challenge try to fly a plane with a large negative wing incidence angle if you can even get it to take off! Personally I find tail heavy aircraft easier to fly than one with severe incidence angle issues!

To simplify my argument or position: A correctly set CG or balance point is extremely important but a properly set wing incidence angle is VITAL if you ever want to have a plane that will fly Rather than being in dispute with your views I am just asking you to widen your perspective!

Have fun!

 

[d8veh]

There are a plethora of posts of persons who have set the CG correctly and the plane still flies, "Like it is tail heavy". My initial post was to try to broaden your response to include advice about things that could be actually considered as either design or build faults.

Yes, i see that too. I believe that many of them are because they're high-wing planes with no down-thrust and no side-thrust on the motor. To me, that's definitely a design fault. i don't think the side-thrust is as important as the down-thrust, though such a plane without side-thrust will veer to the side on take-off, which would be a bit unnerving for a newb.

As soon as I'm well enough to start building again, I'll finish off my Hots 40, then I'll build a Cub with two different power-pods to prove whether I'm correct or not.

 

[Hai-Lee]

Yes, i see that too. I believe that many of them are because they're high-wing planes with no down-thrust and no side-thrust on the motor. To me, that's definitely a design fault. i don't think the side-thrust is as important as the down-thrust, though such a plane without side-thrust will veer to the side on take-off, which would be a bit unnerving for a newb.

As soon as I'm well enough to start building again, I'll finish off my Hots 40, then I'll build a Cub with two different power-pods to prove whether I'm correct or not.

You have the potential to be a great mentor you just need to broaden your approach to include that almost every possible build and design fault may be the cause of handling issues. Also as I was taught, (through forum discussions and counter posts by a great mentor on the forums), repeating the same advice as provided by a hundred others can be extremely off putting or even insulting at times to some especially when they have already checked and rechecked the same thing over and over and yet nothing really improves!

Test building is what it is all about! A mentor is akin to being Sherlock Holmes but without any real access to the evidence often a test build is the only way to assess and resolve the performance issues suffered by others.

I value the membership and really hate it when a member is lost! Just keep up the advice but just widen the scope and you will find you are soon able to nail the problems encountered by others easily.

Have fun!

 

[rmzalbar]

Thank you for the help both of you, I really appreciate it, and don't worry, I'm not going anywhere. I'm a pretty confident solution-seeker and not going to be discouraged away by a challenge.

Certainly if the nose is dropping, it's nose-heavy rather than balanced or tail-heavy, and I need to back up on the weights and set the CG a little more carefully. It's hard to judge the CG very closely because it can take quite a bit of weight before you notice it in the field with a two-finger-balance-eyeball check, though improved accuracy in this way may be something I develop a feel for over time.

The thrust angle is a good idea because although there is an obvious side-thrust designed into the power-pod, it doesn't look like there is any down thrust at all, and that could be contributing to the tendency to want to flip up on takeoff. Watching the build video, I can see that Josh didn't install the power pod flush with the upper surface. He said he was doing so verbally as he shoved it up to the top, but if you look, there's a big gap at the front where the motor leads pass through, certainly enough to give a few degrees downthrust. I actually notched that area out in my build to allow the pod to sit flush, so maybe I fixed something that wasn't actually broken.

Tonight I'm going to check these things out and do some minor repairs, then see about building a better landing gear.

 

[Headbang]

I just looked up that motor. 2700 watts! An 18-inch prop? That thing could have crippled you if it touched flesh. One time I was cleaning my motorcycle chain on the centerstand, and I managed to feed my thumb into the rear sprocket. The big "props off" rule in that situation was to only turn the wheel backwards, and only by hand. Some people thought it was a clever idea to idle the motor while wiping lubricant on with a rag.. and.. yeah. It's a good thing I was only rotating my wheel by hand, albeit the wrong direction. The inertia totally crushed my thumb into a hamburger. Took a long time for it to sort itself out, but it did.

Yep big prop. Most of my planes are 30-60cc equivalent electrics. Good news, I only did that once. And now remove the prop or disconnect the esc without fail. And yep had a motorcycle chain eat a rag while idling to oil a chain, got a good pinch once too.

Sounds like you are on the right track. Last I checked, only way to learn anything was to go out and do it and make mistakes.

 

[buzzbomb]

Some people thought it was a clever idea to idle the motor while wiping lubricant on with a rag.

There's a clever way to lose a finger. Wow. I did once put my last bike up on the stand and idled to clean the rear rim. That scared the heck out of me. It was so not worth it. No prop when testing. Got it.

Like you, I've read that a dozen times. Having your experience relate to something I've got experience with put in perspective. Thank you.

 

[d8veh]

Certainly if the nose is dropping, it's nose-heavy rather than balanced or tail-heavy

No, you can't draw that conclusion. The plane can fly like that for a number of reasons. The first thing to check is the balance point. If that's correct, you have to look elsewhere for the cause. It's the same with nose-up flying.

The thrust direction of the motor is important and it would be different for each different aeroplane. As a general rule, the amount of down-thrust should point the motor in a direction that is in line with the centre of drag. The biggest contribution to drag normally comes from the wings, so the centre of drag will be above the motor on a high-wing plane, so the motor needs to point down a bit so that it's axis points more towards the wings, however, this can be countered by big low wheels or a fuselae that has a lot of atea below the motor.

Side-thrust is a bit more complicated because you need it to counter two main components. Firstly, it needs to counter the torque reaction on the motor. Basically, if the motor is twisting the propeller one way, the torque reaction will twist the plane the other way. Dihedral on the wing will reduce that slightly. Secondly, the wash from the propeller can hit the back half of the fuselage and fin from the side, so it pushes the plane into a yawinging situation. How much it does that mainly depends on the shape of the fuselage and the size of the propellers. Anecdotally, it's worse on short fuselages and big propellers. On a plane like the Sportster, you get massive yaw as you open up the throttle for take-off.

 

[buzzbomb]

No, you can't draw that conclusion. The plane can fly like that for a number of reasons. The first thing to check is the balance point. If that's correct, you have to look elsewhere for the cause. It's the same with nose-up flying.

Granted I still haven't flown, but my gosh I've read a lot. There are so many variables on these foamboard planes. Hai-Lee would say "angle of incidence." d8veh is all about the CG. Many, many posts about the correlation between an actual build, and the way Bix designed it. Just a little warping in the wing changes everything.

If I remember that build vid correctly though, there is some down and side thrust that must be built in. I think getting it right is the hard part. On the upside? You're in the right place to find help.

 

[Hai-Lee]

Granted I still haven't flown, but my gosh I've read a lot. There are so many variables on these foamboard planes. Hai-Lee would say "angle of incidence." d8veh is all about the CG. Many, many posts about the correlation between an actual build, and the way Bix designed it. Just a little warping in the wing changes everything.

If I remember that build vid correctly though, there is some down and side thrust that must be built in. I think getting it right is the hard part. On the upside? You're in the right place to find help.

Do not forget that weight is in the equation. A heavier plane requires more lift!
For a newb it is akin to walking a tightrope, blindfolded, whilst juggling.
For an experienced builder and pilot it is basically the same BUT the blindfold has been removed!

Have fun!

 

[d8veh]

When I used to train newbs without a buddy box, I had the responsibilty of doing the maiden flight with their planes. Some of them were built very badly. The main faults would be twisted flying surfaces and uselages, massive gaps in the hinge-lines and overweight for power. Before me, some f the ther trainers would refuse to fly them with those generally irrepairable faults, which would have been very discouraging for the newbs, so after discussing the risks with the owner, I would always attempt flight as long as the plane met the following rules:
1. C of G more or less where it's supposed to be.
2. Control surfaces moving enough in the right direction.
3. Engine pulling hard enough

I never crashed a newb's plane, though there were a few hairy moments, like one would only turn left and couldn't go as far as straight, so I had to do a load of different sized left circles to get it back to the strip for landing. There was only once that I can remember sending the guy away without flying his plane because the C of G was too far out and we couldn't bodge it to get it close enough, but he was sent away with a clear instruction how to fix it.

So, if you apply those rules and do your pre-flight checks, your plane should fly withut crashing. Your time on the simulator should give you the reactions you need to counter any adverse tendencies at least to get the plane down safely for any necessary adjustments.

Here's my adivce for a maiden:
Before you take your plane to the field, make sure that the propeller is on the right way round and that it pulls the plane forward when you open the throttle.
Before launch, make sure your control surfaces are moving in the correct direction.
Don't fly too far away. Go for height rather than distance.
Don't forget to reduce the throttle as soon as you have a safe height, say 30ft. You need enough to be able to continue to climb. Your experience on the simulator should help there.
After reducing throttle, switch to low rates on your dual-rates switch and keep it there as long as you can control in all directions
Get nice and high, then use your trim switches to get the plane to fly hands free at 1/3 to 1/2 throttle.
As soon as you have it trimmed, start practicing circuits to line up for a landing. Do fly-bys over the landing point at around 30ft until you're ready to land.

Write these things down, and if you have somebody with you, get them to read it back to you at the appropriate time.

 

[eruthutshts]

Our Vision Statement Our vision is to build up a T – shirt structure and deals organization whose brand won't just be acknowledged in the United States of America, yet additionally in different parts of the world. Our Mission Statement https://www.eruthu.com

 

[rmzalbar]

Sounds like you are on the right track. Last I checked, only way to learn anything was to go out and do it and make mistakes.

I agree. Ten fingers is way more than anyone needs, pianists excepted.

 

[rmzalbar]

I built a new power pod with a little downthrust added via the sanding block.. the old one was mushy and springy from nose-ins anyway. I cut away the useless, shredded undercarriage in preparation for making triangular wires as I saw someone else here did.

I spliced in a few pieces of foam to repair a couple of wrinkly melted/collapsed foam areas I had made with my hot air pencil during original assembly. I peeled back the paper on the stubbed wing corners and spliced in healthy bits of foam in there too.

I made a new horizontal stabilizer, as the elevator took a twist somehow on the bench and lost strength, but I haven't put it on yet. Need to made a new cowl piece and an axle wing.

My all-up weight (with battery, but without the lead) is actually significantly under the AUW spec on the plans at 305g vs 340.

The reason I am thinking it's nose-heavy is because for one, I added lead to the nose and two, it noses in severely even with full elevator when the power is off. With a little power, I can get just enough to get a wheels-first touchdown. I think it's the propwash over that big tail that is having the most effect because if I kill motor while up in the air it immediately loses about 75% of its tail authority. I can kinda-sorta dead-stick land it if I dive steeply and flare at the last possible moment, but while that gives me a brief nose-forward attitude, it comes at the cost of an inertially high sink rate and belly slam. I'm thinking I at least should at least be able to flare once without power, and should try to balance the plane to make that just possible.

 

[d8veh]

The reason I am thinking it's nose-heavy is because for one, I added lead to the nose and two, it noses in severely even with full elevator when the power is off. With a little power, I can get just enough to get a wheels-first touchdown. I think it's the propwash over that big tail that is having the most effect because if I kill motor while up in the air it immediately loses about 75% of its tail authority. I can kinda-sorta dead-stick land it if I dive steeply and flare at the last possible moment, but while that gives me a brief nose-forward attitude, it comes at the cost of an inertially high sink rate and belly slam. I'm thinking I at least should at least be able to flare once without power, and should try to balance the plane to make that just possible.

You may well be right, but there are other factors that could cause that too. The way to check is to put your fingers under the wings to see where it balances. It should balance in the range 25% to 33% back from the front of wing. That's not an absolute rule. You might not notice anything if you're slightly out of that range, but you will if you're a long way out. Given the characteristics you had, your first task should be to check it and then adjust it until the plane to balances in that range, probably nearer to 25% than 33% for newb.

The position of the C of G is a very important characteristic. The range I mention above has been proven over donkeys years for planes like yours. It's not like choosing a colour. It's very importantt hat you get it right. Once you have it right, you can then judge the way the plane flies, and you can adjust trim and thrust-lines to get the plane to fly how you want.