Floating wing joiners, in a modern RC glider (how do these function?)

[Konrad]

"As to the end user knowing about the use of tape, frankly if he has flown moulded models for any length of time he will know, because everyone, thousands and thousands of us do it.

I was using it in 1975 when I made my first moulded plane.

It's like reminding the end user that pulling back on the stick will make the model go up - or worse." - Doc

This is very poor documentation. To say that the end user should know about Feature XXX because it has been around for a long time and used by thousands.
With that logic there should be no need to state the CofG or control throws, as it is well understood how calculate this and control throws are common knowledge on the slopes.

I don't know about the slope you fly on, but I and others hate to see destroyed ship particularly when basic information that should be in the manual would have saved the ships.

Like I said on most of my models I tape to seal the wings for when I want the ultimate performance from my ship. Often times when sport flying I don't want to take the time to do this. Yes, my ships usually have positive mechanical retention features and don't rely on tape to hold the wings on.

DSing I'm not aware that any of your (Aeroic) offerings are suitable for this at any real speeds. If you have read any of the write ups by Spencer Lisenby or Bruce Tebo you are aware that we set up back side (DSing) ships very differently than we set up front side ships. Yes, I'd want a lot more carbon in my spar system on my DSing ships than on the front side ship.

Please do your customer base a great service and include all the information they will need to succesfully maiden their new Aeroic model. Requiering that they have a secret decoder ring earned at the school of hard knocks is not going to generated many repeat sales.

All the best,
Konrad

 

[Doc James Hammond]

"BUT it is a free floating joiner system."-Doc

If you are defining free floating as not bonded to the structure then I'd agree. But I would not call a spar (joiner) that is held captive and only allowed to move freely within the 0.10mm slip fit clearance a free floating system.

It's not physically anchored Konrad. It's technically a free floating system.

This slip fit through spar has been used in our models since the beginning of time. I show that even the great old Hobie Hawk has this system.

The joiner is part of the spar, but all parts of the spar are not joiners.

No, the Joiner is a completely separate part that has to do a separate job.

So the joiner that bridges the wings through the fuselage in designs that are free floating are floating spars.
The center part of the spar (joiner) usually see the heaviest bending loads

There is no free floating spar.

It is bonded to the wing skins and the joiner box. It's not free anywhere.

"If you go to the shop, pull out one of my planes and take a really good look at it, you will end all of your gaps in understanding, and save me an awful lot of time. Everything so far discussed is readily apparent just by looking at the physical examples."-Doc
This is far from the truth!

Well, could be. I suppose that different people have different rates of uptake, or deductive skills.

Far too often what I think is self explanatory often winds up not being so! So the RedShift has the same joiner design as the Schwing 88? I can see that, but don't know that!

Exactly the same design Konrad, just the lengths are different.

But to be honest if I was thinking of buying a Redshift, I might not need to know that it has the same joiner design as the Schwing 88.

All of my models use the same design except for the Aresti's and the Gremlin.

The 108 joiner is larger, and longer and both are straight with no dihedral. The Gremlin joiner is round so that it can be replaced with metal tubes or rods, or can be filled with ballast and is also straight.

Cheers,

Doc.

All the best,
Konrad

Hi Konrad, more answers above.

 

[Doc James Hammond]

"As to the end user knowing about the use of tape, frankly if he has flown moulded models for any length of time he will know, because everyone, thousands and thousands of us do it.

I was using it in 1975 when I made my first moulded plane.

It's like reminding the end user that pulling back on the stick will make the model go up - or worse." - Doc

This is very poor documentation. To say that the end user should know about Feature XXX because it has been around for a long time and used by thousands.
With that logic there should be no need to state the CofG or control throws, as it is well understood how calculate this and control throws are common knowledge on the slopes.

I don't know about the slope you fly on, but I and others hate to see destroyed ship particularly when basic information that should be in the manual would have saved the ships.

Like I said on most of my models I tape to seal the wings for when I want the ultimate performance from my ship. Often times when sport flying I don't want to take the time to do this. Yes, my ships usually have positive mechanical retention features and don't rely on tape to hold the wings on.

DSing I'm not aware that any of your (Aeroic) offerings are suitable for this at any real speeds. If you have read any of the write ups by Spencer Lisenby or Bruce Tebo you are aware that we set up back side (DSing) ships very differently than we set up front side ships. Yes, I'd want a lot more carbon in my spar system on my DSing ships than on the front side ship.

Please do your customer base a great service and include all the information they will need to succesfully maiden their new Aeroic model. Requiering that they have a secret decoder ring earned at the school of hard knocks is not going to generated many repeat sales.

All the best,
Konrad

Konrad, I think that any would be sloper will probably visit the slopes a few times before he opens his wallet or gets out the cheque book. During those visits he will probably see a stub mounted wing moulded plane with the wings duly taped.

At the very least he'll do quite a bit of pre-spending research, and if it were me and I could see that the wings had no obvious retaining system, then I'd make it my business to find out how the wings should be retained.

But as I have admitted before, some have different levels of deductive powers.

I don't make DS models on purpose, though a lot of people do DS my planes. Frankly I have seen a near miss with a DS plane which scared me so much that I will never be responsible for actually offering a DS specific airframe.
I can control the construction and the design of my products and thats it. I cannot control the odd idiot who might buy the plane and kill someone, and I would never forgive myself if that happened.

As to instructions, or manuals I do try to give as much information as possible and I will mention taping the wing stubs as a way to hold them on in the future.

I will also mention that on no account, ever, should any plane with a floating joiner system be flown without tape. The next thing would be to fly the plane with no tape and ballast in the wings. A pound weight Tungsten rod or block at 200 MPH hitting you on the head will really and comprehensively F%^K up your entire day. Maybe your entire life.

I do give CG starting positions and also control throws as general safe start points - but I promise you that within two flights by the end user the CG will change and so will most of the control throws.

Generally I have to be honest with you and say that I think adding tape to the instructions is not a bad thing, but I'm also well aware that the person who will buy most of my models is a flyer with quite a lot of experience under his belt.
These people often don't like to be told something really beginner/basic, so I'll probably make a small asterisk paragraph especially for the first timer or beginner.

Generally look the model over to see if there are any control obstructions or any excessive play in any of the controls with the radio switched off.
Plug in the wing plugs.
Remember to tape the wings.
Check the CG.
Remember to check the batteries in the model and transmitter.
Remember to check frequencies if you are using an older radio set.
Remember to turn on the receiver.
Remember to turn on the transmitter.
Remember to make sure the transmitter is turned on to the correct model.
Do a range check.
Check the controls and directions.
If possible get the most experienced flyer at the slope to test fly the plane for you.
Check the sky for other models.
Tell the guys flying that you are about to launch.
If possible, get a helper to launch the model.
Launch the model slightly nose down.
Work up to the full potential of the flight envelope slowly.

I do all of these things without thinking, but as I am rapidly learning, it seems that many things which are logical and sequential to me, are not to others.

However, I honestly don't think there are any omissions in my instructions that would cause a model to be destroyed.

BTW all my planes DO come with a free decoder ring.

Its called Dr. James D. Hammond - 24/7/365 which is a hell of a lot more service than most, if not all other designers give.

Cheers,

Doc.

 

[Konrad]

Konrad, I think that any would be sloper will probably visit the slopes a few times before he opens his wallet or gets out the cheque book. During those visits he will probably see a stub mounted wing moulded plane with the wings duly taped.

At the very least he'll do quite a bit of pre-spending research, and if it were me and I could see that the wings had no obvious retaining system, then I'd make it my business to find out how the wings should be retained.

But as I have admitted before, some have different levels of deductive powers.

I don't make DS models on purpose, though a lot of people do DS my planes. Frankly I have seen a near miss with a DS plane which scared me so much that I will never be responsible for actually offering a DS specific airframe.
I can control the construction and the design of my products and thats it. I cannot control the odd idiot who might buy the plane and kill someone, and I would never forgive myself if that happened.

As to instructions, or manuals I do try to give as much information as possible and I will mention taping the wing stubs as a way to hold them on in the future.

I will also mention that on no account, ever, should any plane with a floating joiner system be flown without tape. The next thing would be to fly the plane with no tape and ballast in the wings. A pound weight Tungsten rod or block at 200 MPH hitting you on the head will really and comprehensively F%^K up your entire day. Maybe your entire life.

I do give CG starting positions and also control throws as general safe start points - but I promise you that within two flights by the end user the CG will change and so will most of the control throws.

Generally I have to be honest with you and say that I think adding tape to the instructions is not a bad thing, but I'm also well aware that the person who will buy most of my models is a flyer with quite a lot of experience under his belt.
These people often don't like to be told something really beginner/basic, so I'll probably make a small asterisk paragraph especially for the first timer or beginner.

Generally look the model over to see if there are any control obstructions or any excessive play in any of the controls with the radio switched off.
Plug in the wing plugs.
Remember to tape the wings.
Remember to check the batteries in the model and transmitter.
Remember to check frequencies if you are using an older radio set.
Remember to turn on the receiver.
Remember to turn on the transmitter.
Remember to make sure the transmitter is turned on to the correct model.
Do a range check.
Check the controls and directions.
If possible get the most experienced flyer at the slope to test fly the plane for you.
Check the sky for other models.
Tell the guys flying that you are about to launch.
If possible, get a helper to launch the model.
Launch the model slightly nose down.
Work up to the full potential of the flight envelope slowly.

I do all of these things without thinking, but as I am rapidly learning, it seems that many things which are logical and sequential to me, are not to others.

However, I honestly don't think there are any omissions in my instructions that would cause a model to be destroyed.

BTW all my planes DO come with a free decoder ring.

Its called Dr. James D. Hammond - 24/7/365 which is a hell of a lot more service than most, if not all other designers give.

Cheers,

Doc.

Well, most of my R/C model purchases are impulse purchases. They aren't that expensive as to require me to perform a cost to benefit analysis.

Nomenclature aside how a wing attaching system transmits transmits loads and control will have a great effect on the durability and feel on the model.

The classic slip fit joiner and socket (like your models) with a clearance of 0.1mm or less will respond very differently that the 1mm to 2mm clearance system we see in the Sanda models.
The physical examination of the Sanda models did not (still hasn't) reveal to me how that true free floating joiner/spar works.

I for one need a detailed break down on how many advanced (or new) systems work, If I'm to understand and extract their full potential. I look first to the OEM for this explanation. And then compare this to real world data (often in the form of failure analysis). If I don't understand how a system works I can't assess whether what I'm seeing is a design feature or a manufacturing mistake!

I fear you give the public at large far too much credit at understanding how systems work. Take for example how many folks understand how the hollow core model glider skin works. You can see this not only in discussion with the owner/flier but also in how they often try to repair these structures. What I see at the flying site I often take with a grain of salt. Far too often poor performing ships (structural and flying) can be traced to the pilot not understanding the system. Yes, I put much of the blame for this on the fact that many manuals don't adequately address how to set up the ship or how to use many of the innovative features we see in the modern high performance gliders. I don't think you want me to try to explain the features of your models at the slope to a perspective customer. This should be done in the manual.

If this discussion has driven improvements in the manual then I feel it was worth the effort. I'd also like to some mention of control geometry. Such as, does Aeroic recommend locked linkages (all three pivot point set up in a straight line) for the flaps? If so, at what position. I mention this, control geometry, because as well get these model up to speed control flutter becomes a real issue. I hate to see a product get a bad reputation when it really was just a setup issue.

You make a good point in that set up in the manuals should be thought of as starting points. I've seen far too many fliers refuse to move the Center of Gravity around as part of their flight trimming efforts. Like I said the information in the manuals should give the pilot a fight chance at having a successful maiden flight. I'd like to see a statement that after the maiden move the Center of Gravity around as the maiden flight indicates to get a model into proper trim. I recall that when your Stormbird first came out it got a lot of press for be sluggish. I think you said the center of gravity was to be placed at 90mm, maybe even further forward. Today all three of the Stormbirds I've seen all have the CofG placed around the 100mm mark.

I'm glade to see that I can accurately access the suitability of a model as a DS ship.

LOL, so true about the decoder ring. I and others thanks you!

All the best,
Konrad

 

[Doc James Hammond]

Hi Konrad:

"I recall that when your Stormbird first came out it got a lot of press for be sluggish. I think you said the center of gravity was to be placed at 90mm, maybe even further forward. Today all three of the Stormbirds I’ve seen all have the CofG placed around the 100mm mark."

This is a perennial problem for the designer.

Now I know exactly where the CG should be, but what I don't know is the flying ability of the owner. Same goes for the control settings. So I put the start CG back to a place that I know will leave the plane docile for the first flight, and use conservative start control settings that I know won't make the model twitchy and appear over responsive.

These models are not meant for first time flyers and I describe most of them as "High performance sports models" Hopefully you are buying an airframe with a potential performance at the top end of what is possible for the size and duty of the airframe, but that will never stop someone who does not have the right skills from buying it. Now if I had given the real CG, and control settings such a person would re-kit the model in very short order and would complain about it being un-flyable. That is an omission, or a mistake which would destroy the model.

But I'm happy to say that as part of the proof that I am on the right track, the Stormbird - which you mentioned - has been flown well with a CG as far back as 110mm. Thats a total range of 20mm (90-110mm) and is still well flyable and easy to land; which when you think about it is pretty incredible in a high performance narrow chord wing.
By the same token - when you get the CG right (for YOU) its fast and aerobatic yet slows down well for landing and is in fact a pretty incredible model for a sports plane.

Being a Decoder Ring has other disadvantages too. Since I make myself accessible and welcome comments and suggestions (Of a constructive nature) from anyone, I again fall foul. Too many people who know enough to be dangerous but not enough to realise that they don't know enough begin to wade in. Every single model I have ever designed has had suggestions and sometimes outright demands that I change it from this type of armchair professor.
In fact very few actually valid comments, or constructive criticisms have ever been made.

Maybe I should be like the other designers and refuse to answer any questions, then look down my nose at anyone who is not a past or present world champion - and believe you me, that really happens.

I still have to be polite, but I can tell you that sometimes it taxes what little patience I have far past breaking point..

Cheers,

Doc.

 

[Konrad]

Hi Konrad:

"I recall that when your Stormbird first came out it got a lot of press for be sluggish. I think you said the center of gravity was to be placed at 90mm, maybe even further forward. Today all three of the Stormbirds I’ve seen all have the CofG placed around the 100mm mark."

This is a perennial problem for the designer.

Now I know exactly where the CG should be, but what I don't know is the flying ability of the owner. Same goes for the control settings. So I put the start CG back to a place that I know will leave the plane docile for the first flight, and use conservative start control settings that I know won't make the model twitchy and appear over responsive.

These models are not meant for first time flyers and I describe most of them as "High performance sports models" Hopefully you are buying an airframe with a potential performance at the top end of what is possible for the size and duty of the airframe, but that will never stop someone who does not have the right skills from buying it. Now if I had given the real CG, and control settings such a person would re-kit the model in very short order and would complain about it being un-flyable. That is an omission, or a mistake which would destroy the model.

But I'm happy to say that as part of the proof that I am on the right track, the Stormbird - which you mentioned - has been flown well with a CG as far back as 110mm. Thats a total range of 20mm (90-110mm) and is still well flyable and easy to land; which when you think about it is pretty incredible in a high performance narrow chord wing.
By the same token - when you get the CG right (for YOU) its fast and aerobatic yet slows down well for landing and is in fact a pretty incredible model for a sports plane.

Being a Decoder Ring has other disadvantages too. Since I make myself accessible and welcome comments and suggestions (Of a constructive nature) from anyone, I again fall foul. Too many people who know enough to be dangerous but not enough to realise that they don't know enough begin to wade in. Every single model I have ever designed has had suggestions and sometimes outright demands that I change it from this type of armchair professor.
In fact very few actually valid comments, or constructive criticisms have ever been made.

Maybe I should be like the other designers and refuse to answer any questions, then look down my nose at anyone who is not a past or present world champion - and believe you me, that really happens.

I still have to be polite, but I can tell you that sometimes it taxes what little patience I have far past breaking point..

Cheers,

Doc.

Yep, In my talks with designers like Lee Renaud and Joe Bridi they told me that on their plans they made recommendation to give the modeler a fighting chance at a safe maiden flight. They did not want their designs getting a bad reputation because the newly built model snapped while going up the winch line.

I like that the design by Hanno Prettner (many time F3A world champion) had all the needed data for setting up the plane for its maiden flight. I also liked that Hanno also published the information on how he had his plane set up. These were, to a model, very different. *

Today I like designers like Jerry Small and Danny Kane, in their EF-1 designs they go into great detail, in their manuals, on how to trim a pylon racer . While the perspective racer may be an experienced sport flier he might not understand the requirements for a smooth pylon racer.

Even I set up my models differently depending on where they are in their life cycle. Like after a major repair, I'll move the CofG forward for the re-maiden. For this repair I did just that as I didn't have any fixturing to ensure that the wing was repaired straight. Should I have a twist in the wing I wanted a fighting chance of being able to land the ship in one piece and make appropriate adjustment.
https://forum.alofthobbies.com/inde...olded-models-60-glass-and-rohacell-racer.367/

I trim (set up) my aerobatic models very differently than I set up my pylon models. For aerobatic models I trim for a zero G trim condition (that is I have to hold the same amount of stick both upright and inverted). I got a kick out of allowing a pilot (good pilots) to fly my ships. This was in the days before flight modes. I could hear the panic in their voices as they were adding in a lot of up trim to get what they felt was a properly trimmed hands off straight and level flight (one G trim condition). I fly with an "aft CofG" so as to minimize the amount of stick offset between upright and inverted flight. I would not want to use this set up for maiden flight!

I don't think you want your perspective customer to turn off his brain. How else would he be able to discern the unique advantages of your designs? I for one have never said that your designs where inadequate and needed to be changed. I question many of the features I see in your designs to get a greater understand of these features. Yes, I use my experience as the foundation to ask these questions. Now I do offer market feedback (my opinions), you have asked for this from time to time, as to what “I†the customer sees as marketing issues, not engineering issues. This has covered issues from esthetics to the manual. Again these are my thought as to why I have or haven’t purchased an Aeroic design. I do this in hopes that it will help with the overall customer experience (mine) and your sales.

Now in my review, write ups, I try to state what I see as a issue, why I think "X"is an issue and offer my work arounds. Unless something is a gross violation of engineering first principles I rarely say X is a design flaw.

Yep, I found it distasteful that OEMs would ask for information, yet wouldn’t want to pay a consultation fee!

*This data as to what the designer thinks is the optimum set up helps a lot in setting up the plane. Like linkages, servo placement and for our slope gliders the ballast tube. I've seem guys center the ballast tube over the CofG mentioned in the manual. Only to find that they wind up with nose heavy ships as they ballast up.
(I place the ballast tube after I have her trimmed. Or I keep the tube too long (aft) and add spacer for trim blocks to be added to ensure that the CofG is kept in place even when fully ballasted.).

All the best,
Konrad

P.S.
When I buy a model I'm buying more than just carbon and epoxy! I'm buying an engineering design and I demand, as a customer, that the manual have the data to help me extract the performance that the designer has imparted into that design.

 

[Doc James Hammond]

Here is the Stormbird being sluggish on the second test flight at Ivinghoe Beacon UK.

There is no ballast and the CG is WAY, WAY too far forward.

It did get a lot faster with the correct CG, then better still with some ballast, but as you can see at 90mm its still pretty lively.

Cheers,

Doc.

 

[Doc James Hammond]

Final testing at Captain Cook's monument UK - Still no ballast but the CG is closer.

Quote from Test Pilot Greg Lewis:

"I first tried to fly at Captain Cookes Monument in the late 80's. Finally after all these years we made it there with a solid wind straight on the main face. It was a total pleasure to fly four of James Hammond's plane's there.

We started with the Stormbird and the Schwing. So we could test them back to back. Then onto the Aresti 2M. The wind was picking up all the time. Peaking at 35mph constant gusting 55mph.

So we put 2.5kg of ballast in the big Aresti 108. To say it was majestic was an understatement. My flying mates for the trip were left wide mouthed as we timed the stall turns having 5 seconds of vertical climb and 2.5 rolls on the way down.

Captain Cookes Monument is a big hill with big lift and the big Aresti was just amazing to fly.

Having flown the Stormbird on it's own recently. It was great to fly the Schwing in the same conditions. Both planes are rewarding and flattering to fly.

But the Stormbird in particular is not for the faint hearted. It is really fast and just keeps accelerating. We need a 10-20 mph day to see how it goes against the Schwing in light lift.

Perhaps we can persuade James to build a super strong version and see how it goes on the dark side of the hill.

It really does go and is rewarding to a pilot who pushes for speed."