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Spada 3M
- Thread starter Doc J
- Start date
Doc J
Very Strong User
Konrad!
We are not normally talking about round hollow monocoques (like a model tail boom) for wing spars for obvious reasons - though for smaller models they are pretty good, and do offer great scope for different material joiner rods and ballast storage.
As to making crane booms triangular, isn't that because the triangular section made of round tubes is economical and the closest in strength to a round section? As you say - form follows function.
Doc.
Konrad
Very Strong User
In the smaller models I believe tube spars are used for ease of manufacture. Most designers don’t like them, as little of the fibers are actually placed where the mass is used to great effect.
The crane boom has to deal with very high loads in one direction and some much lighter side load. A tube offers resistance equally 360 degrees. The crane boom and maybe our tail boom don’t see loads equally (360 degrees). So the boom tries to put material where needed.
The round tail boom is good as we really don’t know how the boom will whip in a crash. But with another cross section and lay up we can try to define how the boom will perform.
The crane boom has to deal with very high loads in one direction and some much lighter side load. A tube offers resistance equally 360 degrees. The crane boom and maybe our tail boom don’t see loads equally (360 degrees). So the boom tries to put material where needed.
The round tail boom is good as we really don’t know how the boom will whip in a crash. But with another cross section and lay up we can try to define how the boom will perform.
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Raymond Gaskins
Very Strong User
I will jump in and say that I find these exchanges stimulating. While I have a strong science background, I am not an engineer. I have a strong interest in learning all I can about the design, manufacturing, and flying of these planes and enjoy the discourse offered in this forum.
So keep it up and let me learn and I will be a quiet observer unless I have something profound to offer!
Raymond
Doc J
Very Strong User
I love them on the smaller models - Light, strong, easy to get, easy to use, many different fibre orientations available, spiral, straight, straight/wrapped etc, lots of wall thicknesses can be had, can take ballast, the joiner rods can be carbon, alumnium or steel etc.
Added to that, should you (heaven forbid!) want to make a twisty...well, I rest my case.
OK first I want to take back what I said originally - I was having a Doooohhh moment! In fact, most but not all crane booms are square in section and not triangular, though many are. As you say, round tubes offer the same load resistance for 360 dgrees, but in fact the loads and the stresses to be withstood in any direction are to a large extent designed in to the construction of the structure.
There will always be that one time where for some reason the structure exceeds its design limit and fails and this is because the crane boom does NOT see the loads equally.
Its designed to lift loads from the deck up, against gravity,more or less in one direction only and apart from any unplanned side or other forces, thats what it does.
Aha - and there you have it. We are now blessed with two lovely variables to help us:
1. Using CAD and CNC we can design the boom to any shape we wish. If the side forces are a factor then in theory we can make the boom elliptical in the side plane, or in fact orientate it to any other plane that concerns us.
2. We have complete control over the composite materials type, amounts, and orientations, and use this as a strengthening or stiffening method in order to counteract stresses too.
Cheers,
Doc.
Doc J
Very Strong User
I think we all learn here. I certainly do.
Its this open, friendly exchange of ideas and opinions from people skilled in thier own disciplines, or those who are not so skilled, but are eager to learn that make this such a great forum.
If you tried to do this on RCGropes, you'd immediately get 15 people strongly disgreeing with you, all "armchair professors" all of whom have never designed anything, and a then few Trolls thrown in, just to darken the mix.
Toxic actually.
Long Live Aloft Forums!
Doc.
Konrad
Very Strong User
One of the stiffer, lighter and proven more durable are the booms found on the Freestyler 5.
I don’t think it shows up well but the fuse is changing cross section from the non tapered straight sided rectangle adjacent to the wing to a nice triangular cross section tail boom with the apex at the top. This puts a lot of fiber on the bottom to deal with the left and right side loads of a typical bad landing ( my normal stuff).
I’m really starting to like what I see structurally in the Freestyler.
Now if they understood what Schumann observed then I think they would have one of the greatest designed F3F racers. But as I don’t think Schumann, an amateur aerodynamicist, characterized what he observed. So maybe the spanwise flow from the tip to the root at or near the stall isn’t understood by many.
Now your wing on the Redshift handles this very well and is why your 18:1 aspect ratio wing works so well at high Cl numbers (turns) when others not so much.
Like I’ve said I love the wing, but the fuse not so much*. So unless there is a reason to keep the fuse cross sections similar to the mk1 I see room for improvement, both in aerodynamic and structural geometries.
*one big plus I see in the mk1 fuse are those shoulder fillets at the wing LE. I know they have saved my wrecks from the wing totally crushing the fuse in that area. Now it needs to be said that the price of the RedShift was a little over Half that of the Freestyler 5. So warts and all I loved the Redshift enough to own 3. In fact one has just risen from the dead! Working the radio set up right now.
I don’t think it shows up well but the fuse is changing cross section from the non tapered straight sided rectangle adjacent to the wing to a nice triangular cross section tail boom with the apex at the top. This puts a lot of fiber on the bottom to deal with the left and right side loads of a typical bad landing ( my normal stuff).
I’m really starting to like what I see structurally in the Freestyler.
Now if they understood what Schumann observed then I think they would have one of the greatest designed F3F racers. But as I don’t think Schumann, an amateur aerodynamicist, characterized what he observed. So maybe the spanwise flow from the tip to the root at or near the stall isn’t understood by many.
Now your wing on the Redshift handles this very well and is why your 18:1 aspect ratio wing works so well at high Cl numbers (turns) when others not so much.
Like I’ve said I love the wing, but the fuse not so much*. So unless there is a reason to keep the fuse cross sections similar to the mk1 I see room for improvement, both in aerodynamic and structural geometries.
*one big plus I see in the mk1 fuse are those shoulder fillets at the wing LE. I know they have saved my wrecks from the wing totally crushing the fuse in that area. Now it needs to be said that the price of the RedShift was a little over Half that of the Freestyler 5. So warts and all I loved the Redshift enough to own 3. In fact one has just risen from the dead! Working the radio set up right now.
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Doc J
Very Strong User
The new Spada fuselage is smaller in cross section than the FS I think. Its not even half of the cross sectional area of the MK1. And it follows the Heorner doctrine.
I'll say it again: The new Spada fuelage cross section is smaller than the FS I think. Its not even half of the cross sectional area of the MK1.
I thought that could be easily seen from the drawings I posted?
The same shoulder fillets are still there on the new Spada.
This is a bit of an anomaly. It used to be that the (actual)cost of making a model in E-Europe was more than that in China, and by a fair amount. Thats no longer true. Prices for the models from China have risen, though the large proportion has been due to materials price rises.
However, it is still true that the prices for the Euorpean models are high because they can charge high prices and not so much due to economic constraints or changes. They charge more money and they make more money. This is why I'm not marketing the Spada as an F3f model That space is overcrowded.
Spada will be a fast, high-end 3M sports model. The fact that it will be pretty competitive in F3f is purely cooincidental.
The end user price will reflect that.
Frankly I'd rather sell more models for lower prices than try to compete with the 20 plus F3f-specific models there are for sale right now. In this case more people will be able to afford the model, and I know well that I have the ability to make it really competitive.
I'm your Doctor, so on these things - trust me.
Doc.
Konrad
Very Strong User
A rose by any other name would smell as sweet. My appoligies to Bill...
Spada will be a fast, high-end 3M sports model. The fact that it will be pretty competitive in F3f is purely cooincidental.
...
Doc.
Doc J
Very Strong User
Surpise surprise! Konrad, I have been telling you this for a couple of days - what are you on? I want some!
This is the Spada first mockup but I don't have Redshift nose to compare it to. My fingers are not very big though.
Doc
Doc J
Very Strong User
No. I have given enough information here, Konrad and anyway that would need a bunch of special views made.
Frankly I'm leery that stuff I put here might end up on another Zhou model.
Yep.
Cheers,
Doc.
Konrad
Very Strong User
Hum, all the tower cranes swinging wildly over the city have triangular cross sections booms. The side load that I was thinking of that might mimic the side load of a whipping tail boom is the force needed to swing the heavy load over a spot.
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Doc J
Very Strong User
Actually my recent files have been done using Onshape, no Catia for a couple of years.
There is a limit to how much information can be given away prior to the model actually coming out.
This crosses it.
Cheers,
Doc.
Raymond Gaskins
Very Strong User
Hill Hobbit
Very Strong User
That’s a good one Raymond! And, really that, for Konrad, is the reason for what I said in posts #26 and #28. I’ve been a rc car racer since 1979 to date, 4 years of which on a professional basis as the editor of an rc car magazine. As such, I was privy to a great deal of information from designers and manufacturers of their products. This was all on a non disclosure basis of course. I even took part in test sessions, driving cars back to back to give my thoughts on development mods.
In the model car world, and to an extent racing gliders, the saying is “What wins on Sunday, sells on Monday”, so new ideas that prove to work are kept under wraps until the new parts/car etc are available to buy etc. At big race meetings, it’s really common to see in the pits that the top drivers, known to be driving either brand new cars or development parts on an existing chassis, cover their cars and/or make it plain that they don’t want photos taken.
The same goes for F1, in which I have also worked. There’s no way in the World that open forum discussions re design and development take place. Mercedes don’t contact Ferrari to tell them “hey we’ve just found something worth 1/10 of a second per lap, and this is what you do to achieve the same”.
This is the reasoning for the posts I put up.
I don’t want a ‘battle’ with anybody, on an Internet forum or in life, to which I have a very tenuous link nowadays. I am certainly not actively suppressing development of James’s Spada Konrad, and where does that idea come from anyway? Two of the three UK Redshift team pilots are mates of mine, so I’m very well aware of their thoughts on the Mk1. And, these guys are GOOD…
Konrad et al, you have a good day. Me, I’m going flying with my Forza and my 11 year old and never repaired, totally problem free RCRCM Typhoon…
Have fun
Jonty
In the model car world, and to an extent racing gliders, the saying is “What wins on Sunday, sells on Monday”, so new ideas that prove to work are kept under wraps until the new parts/car etc are available to buy etc. At big race meetings, it’s really common to see in the pits that the top drivers, known to be driving either brand new cars or development parts on an existing chassis, cover their cars and/or make it plain that they don’t want photos taken.
The same goes for F1, in which I have also worked. There’s no way in the World that open forum discussions re design and development take place. Mercedes don’t contact Ferrari to tell them “hey we’ve just found something worth 1/10 of a second per lap, and this is what you do to achieve the same”.
This is the reasoning for the posts I put up.
I don’t want a ‘battle’ with anybody, on an Internet forum or in life, to which I have a very tenuous link nowadays. I am certainly not actively suppressing development of James’s Spada Konrad, and where does that idea come from anyway? Two of the three UK Redshift team pilots are mates of mine, so I’m very well aware of their thoughts on the Mk1. And, these guys are GOOD…
Konrad et al, you have a good day. Me, I’m going flying with my Forza and my 11 year old and never repaired, totally problem free RCRCM Typhoon…
Have fun
Jonty
