Aeromodellers have always been attracted by speed, if not addicted. But when you come to the speed evaluation, you quickly discover that people are very often optimistic (like measuring altitude). This is why a speed radar is interesting for our hobby.
If you don’t want to invest in an expensive radar gun, there is now a very convenient device that do the same for less money, but especially that will fit in your pocket, so that you can bring with you all the time. It has been made possible by using a much smaller, flat antenna to create the same type of signal that the horn creates in a radar gun.
I bought one for me few months ago. My objective is to have a means to measure the speed of my sailplanes when DSing.
The Pocket Radar has the size à a cell phone, and is able to measure the speed of moving objects from 11 to 600 km/h. It uses 2 standard AAA type batteries and comes with Alkaline batteries included. It comes in a very nice box that will protect it during transport.
Its accuracy is about +/- 2 km/h. If you point the radar at an object moving sideways, you won’t measure anything. This is what we usually call the Cosine error. Just remember some trigonometry when you where at school and you will quickly understand. Few figures: Within 8 degrees of angle from the moving line of the object you measure, the accuracy is about 1%, at 18 degrees it is about 5% of error, and it goes up to 30% of error with 45 degreed of angle.
The Pocket Radar is pretty easy to use: Hold the radar in your hand like a cell phone camera and simply press and release the big red button on the front of the Pocket Radar while pointing the moving object. When releasing the button, the measure will appear on the screen. If you do not release the big red button, the radar will continue to send out repeating small pulses and displaying a measure approximately every second.
You can configure the Pocket Radar with different speed units: MPH (Miles per hour), KPH(Kilometers per hour), FPS (Feet per second) and MPS (Meters per second).
To do so, just press and hold the black RECALL button. While holding the RECALL button down, press and release the big red button. Now release the RECALL button. The current selected units should blink (at the bottom of the display). Then each time you press and release the big red button, the units will advance to the next possible state (miles per hour, kilometers per hour, feet per second, meters per second).
Press and release the big red button until you see the units that you want to use blinking on the display. They will continue to cycle through each time you press the big red button. Finally, press and release the RECALL button and you will lock in the units displayed on the screen.
The Pocket Radar can store 10 measurements that you can scroll using the black “RECALL“ button.
2 Alkaline AAA batteries can provide up to 10,000 speed measurements which is not bad. The battery indicator on the LCD display will help you determine when to replace the batteries.
According to the manufacturer, the Pocket Radar can spot the speed of a car from about a 800 meters away or the speed of a baseball from up to 36 meters away.
I found the Pocket Radar to work pretty well for sailplanes. After a long dive, or while DSing, it always give a measurement. It is very seldom when it doesn’t display something.
More than that, as soon as I exit my Pocket Radar on the slope, everybody wanted to play, asking for a speed measurement of their plane.
You will see on this short video how easy it is to use the Pocket Radar:
In conclusion, the Pocket Radar is very nice device, that will cover most or our use. Of course if you are targeting the DS world record, then you will need another radar gun, factory modified to go higher than the 700 Km/h achieved today. For other pilots, the Pocket Radar give you a good progression margin before to hit its limit.
Despite cold temperatures, I spent the afternoon on the slope to fly the Ambrosia F3X in good wind conditions (Around 40 km/h). I flew it with 650gr of ballast over the 1300gr it can carry.
If I would have to describe the Ambrosia is very few words, I would definitively say: “It tracks extremely well !“. Thanks to the fin and the full moving cross tail, the Ambrosia is a pure joy to pilot. It is fast, but especially, it is easy to fly fast, which is a very good capability from my point of view. You don’t have to fight with the plane, to correct trajectories all the time.
I did hundreds of laps and turn, and I have been very impressed by its behavior in Energy Management turn style. It is so easy, remains stable, go high without slowing down. The elevator is smooth and very precise. No drag induced by a control surface, the full tail is always perfectly aligned.
The Ambrosia carried the 650gr easily, and I think I could have put more ballast without problem.
The DP section delivers very good performances, and speed. Acceleration are good and the energy retention also. The next step will be to confront the Ambrosia F3X against other gliders, to have some references and see how it is compared to competitors.
The survey ended few minutes ago and gave interesting results. Thank you all for your participation to the survey !
Before to comment the results, it is important to mention that the survey concerned mainly Europe, and especially France as you can see on these per country statistics for last month.
Let’s now have a look to the results:
Without surprise, Futaba FASST arrives in first position. FASST has been introduced at the beginning of the 2.4 Ghz, as the first FHSS system, and appeared to be reliable from day one apart few recall concerning the sensitivity to the temperature of one receiver chipset. But if Futaba represents 1/3 of the market, things could change quickly if they are not releasing the telemetry which is today the major weakpoint of their offer.
The surprise is the second rank of Jeti. Jeti was not particularly reliable with their FM receiver, but their 2.4 offer is pretty well designed, reliable, and Jeti is the very first brand to propose and deliver telemetry and various probes, not only “dream-ware”. With Jeti, telemetry is real ! Jeti is very much appreciated in the glider world. Weak point is that Jeti offers only modules and receivers, no transmitter. But they officialy announced a transmitter family for beginning of 2011.
In third position another surprise with MPX, which is very new on the market compared to some other brand. But despite a late arrival, MPX reaches 15% of the market. They offer a home made 2.4, not relying on industry chipset. As MPX is used widely by glider pilots, most of them migrated to 2.4 within the same brand.
Then we find Spektrum followed closely by Assan. Spektrum is more used by helicopter or airplane pilots, but less by glider pilots. One of the reason is the poor possibilities of the spectrum transmitter. Maybe the recent DX8 will change things. Assan, on his side is taking advantage of their aggressive pricing to take some market share. But the current trend is that Assan is slowing down because of the lack of telemetry and also transmitter. They are probably hitted by the recent progression of FrSky who proposes aggressive price AND telemetry with the interesting analog probe input on the receiver that allows to develop his own probe.
It interesting to see that “Other” represents 13% of the market. In Other we find Weatronic who recently left Graupner after the introduction of the HoTT system. We find also FrSky, and some other alternative brands.
Hitec remains marginal, which is a surprise as the Aurora 9 is a nice transmitter with plenty of Glider capabilities. In addition the Hitec 2.4 appears to be a reliable system. XPS/IFS is also marginal.
Finally Airtronics/Sanwa suffers a lot of a very poor representation/distribution in Europe and especially in France. For example, the French distributor (scientific france) is inexistent. I know that Airtronics is very popular in US and the SD10G is a good transmitter to use for gliders.
This picture of the 2.4 market will change drastically in the coming months as the war will reinforced. It will be interesting to do another survey in one year, in order to see the evolution.
Well, the weather conditions were totally calm air, no wind at all with a temperature of 4° celcius. Hopefully, all the snow melted since last week-end, so the slope was accessible.
It was defintively not a weather for a maiden flight, but because I was on the slope, I didn't want to return home without launching the plane once, do a circuit and land.
Surprisingly the first flight was longer than expected and I was able to do few circuits in dead air, with flaps, before to land, very encouraging.
I have been able to see the good lift provided by the section, and the good handling of the Ambrosia, at very low speed, with no bad habits, no stall.
Now, I'm waiting for better condition to see what the plane is capable. Maybe tomorrow I will drive 1 hour to go to another slope where the wind could blow a bit more according to the weather station installed near the slope for paraglider.
Jeti posted a press release on their website confirming the release beginning of 2011 of a 2.4 Ghz transmitter family (which means not one but several transmitters) a also a brand new slim receiver especially designed for glider nose.
This is excellent news !
By the way, don't forget to answer the survey which will give us a better undeerstanding of the market share of each manufacturer.
I thought it would be interresting to know the market share per brand, as we are in the middle of the war. Please answer honestly to the survey on the right of the page. The more I get answers, the more the result will be representative !
Lans-en-Vercors is a village in the Isère department in south-eastern France, near Grenoble. After the heavy snow falls last week, I drove there to do some aerial pictures and video. Sunny weather but freezing temperature with -8 degrees (celcius).
Lans-en-Vercors is located in the Vercors a beautiful massif of mountains. The Vercors massif and surrounding areas are protected as a regional park (Parc Naturel Régional du Vercors in French). Some especially wild and remote places of south eastern Vercors are in a more protected area named Réserve intégrale des hauts plateaux du Vercors (Vercors high plateaus reservation). These mountains were used as a natural fort by the French Resistance during the second world war.
Vercors is a perfect place for outdoor activities: Nordic Skiing (One of the largest Nordic skiing system of Europe), Alpine skiing with 7 ski resorts, Paragliding, Canyoning and Caving, base jumping, and of course aeromodelling with one of the most thrilling competition of the french cup with vertical cliffs.
This is about Sailplane but not RC. "Sailplane Grand Prix" is new gliding racing format that take advantage of the latest techonolgies to allow the spectators to watch the race real time with onboard camera, real time simulation.
The following video explain everything with in addition superb video sequences. Unfortunately, it is not broadcasted on the main channels in France. Maybe some of you have seen it
After buy few different ball link pliers that was not working at all on my gliders (for tailplanes), I decided to build my own. I use it to plug or remove the ball link on the tailplane. It works like a charm.
To build your own ball link pliers, you just need a low price flat nose pliers, and with a mini drill, you grid a slot in one of the nose:
When 2.4 Ghz appeared few year ago, lots of people were wishing a convergence of the systems in order to be able to mix brands together like we can still do with PPM radio.
But this dream is, from my point of view, flying away with what we see currently on the market, and worse than that, large manufacturers are suppressing PPM transmitter from their catalogue to offer only 2.4 native transmitters.
Today, it is impossible to find a Futaba T10FG. Graupner is selling out the MX12s and MX16s. When you open big shop catalogue or website, you don’t see anymore PPM radio.
Another example with Multiplex who is protecting their transmitter by supressing the PPM signal on the Royal Pro. When you send a Royal Evo for maintenance, it comes back with the firmware of the Royal Pro !! too bad ...
This prevents the end customer to buy a PPM transmitter, then install any 2.4 HF module of his choice. All alternative brands, with affordable prices, are in danger in a near future. I think this explains why Jeti will release a transmitter beginning of 2011.
We are clearly in the middle of the 2.4 war, and this war will not stop before some players die. We are of course hostage of this situation. As soon as we choose a system, we are prisoner of this brand.
Following my post about the test results of the DS6125, I received several mails asking me about the difference between the max torque measured by Servormances and the max torque indicated by MKS. More generally the question is the same for all other servos tested with Servormances. So I think it was necessary to come back on that topic and give more information in order to avoid any confusion.
As we say in french, we can not compare apples with oranges, and this is a little bit the case here, so let me develop further:
On the manufacturer specifications the max torque mentionned is the blocking torque, that is to say the torque at which the servos cannot rotate anymore. The servormances team took another approach. Servormances max torque is very restrictive as the value published respects the following criteria:
Precision is within a range up to 1.5°
Speed is better that 0.8s for 60° of travel
Power Consummation is under 80% of the max consummation measured
Taking the DS6125 under 6v as an example, it means that, according to Servormances, this servos is working under normal conditions at 2.6 Kg/cm. In other words, you won't notice any degradation. Then the blocking torque can be much higher. Just to give you an idea, 2.6 kg represent twice the ballast the Ambrosia can carry. not bad !!!
This comment is valid for any servos. In fact, what is the most representative for us, the pilots, is the "usable" torque, and the objective of Servomances is to test servos in the very same conditions in order to be able to compare them.
To finish, I let you enjoy the demonstration of the blocking torque on the DS6125 with this video from the manufacturer. Pretty impressive !
I finished the Ambrosia this week-end. I found in a DIY shop a square steel tube with the right dimension, 14x14mm, and some wood for the spacers.
I made slugs length in order to have 2 slugs per compartiment, that is to say 4 slugs per wing. What is interesting is that compartiments are located on each side of the joiner which garanties that the CG will not move too much when ballasting.
Each slug is about 160 g.
And the total ballast weight is about 1300g, which is perfect
I also did the CG balance of the plane and moulded the lead for the nose. I needed around 150g of lead which is not too much considering the fin and tailplane which is usually heavier than a V-tail.
The total weight is 2250g. The Ambrosia F3X is ready for maiden :) !!!
First flight next week-end if the weather is cooperative. We had snow falls the last days ...
Assembly continued with the wing servos and pushrods installation. The Ambrosia F3X comes with the brass ring-screws. You'll need 8 clevises (M2), some threaded rod and also aluminium tube with an internal diameter of 3 mm. First of all, I grinded 4 clevises (that will be on servos side) in order to use the servos arm hole the closest to the axis.
Then, the servos being in place in the wings, I cutted the threaded rod at the right length, glue with some rapid epoxy the clevis on the ailerons/flaps side. Once dry, I glued the clevis at the other end, and inserted a 3mm aluminium tube to make the control rod more robust and stiff. The reason I fix the clevises with rapid epoxy glue to to suppress any possible slope on the command. You will also notice that the ring screws are not glued in place. It will be done at the very end because once in place, the clevises cannot be removed anymore.
Then, I drilled the wing plug housing at the root of the wing. The housing is at the perfect dimension for the green MPX style plug.
The servos are screwed on their frame, and the command pushrod put in place. The ring screw is glued with epoxy at that time.
Same for the flaps. The only difference is the servo arm neutral position with is different in order to obtain more travel down for the airbrakes:
The servo covers are cut, following the moulding mark. They fit perfectly:
I prepared a small ON/OFF switch on an epoxy plate which is then screwed on the servo tray. The switch is small enough to let the space for the receiver.
The battery has been soldered. Cells are hot glued together. A transparent shrink tube allows a nice finish.
To complete the assembly, I just need to install the receiver and program the servo travels and neutrals, do the balance lead to obtain the right CG, then build some ballast. The ballast tube square section is 14x14 mm . I found a steel tube of this size and I will melt some lead in it.
I continued the assembly with the servos installation, in the fuselage and in the wings. In the fuselage, the DS6125-H are simply screwed with the woodscrews provided.
Pushrods are made from metal tube with a external diameter of 2mm. First, I cut them at the right length before to fix a M2 treaded coupler at the end. I used MPJet couplers made from brass because they are execellent quality.
Usually, I glued, then pinched the M2 treaded coupler on the pushrod. Prior to that, I inserted 5cm of 1 mm pianowire in the tube in order to not crush the tube when pinching the coupler.
I started also to have a look on the battery to use. This is straigth forward: 4 eneloop cells mounted in 2+2 format will take place easily in the nose.
They enter without any problem by the canopy, once servos are in place. This is a good point because the canopy is not that big.
On the wing side, I prepared the servo holes to receive the wood frames. Once positioned, I glued the frame with rapid expoxy (10 mn R&G epoxy), put the servo in place with a very thin plastic film in between, ajust the position of the frame & servo in order to have the servo horn well aligne with the control horn.
I put a ballast on top of the servo and let everything to dry smoothly all night long.
This morning I checked the result, and all is perfect. The DS6125 fit perfectly in its wood frame which is well glue
The result is clean and ready to receive the control rods which is the next step of the assembly.
Taken last saturday using an EasyGlider equiped with a Sony cybershot DSC-W350. It was already late in the afternoon, and the shadow created by the sunset and the mountain was not ideal. The picture is above the south of the grenoble valley, where are located some chemical plants.
If you look carefully on this second picture, you will see a small part of the Mont-Blanc, behind the mountain range the highest summit in Europe with 4807m
The mountain range is Belledone: Belledonne (French: La chaine de Belledonne) is a mountain range (French: massif) in the Dauphiné Alps (part of the French Alps) in southeast France. The Belledonne range is approximately 60 km (37 mi) long by between 10 km (6.2 mi) wide. There is no road that cuts across Belldonne (source Wikipedia).
One of the legend of the aeromodelling died during the afternoon of the 11th of november, only 2 weeks after his retirement has been announced officially during a press conference in Friedrichshafen. Hans was 81 years old.
Raviole Soaring is unformal regional winter league competition in order to be busy and have some practice during the winter. We selected small slopes, not high in order to not have snow, or at least a low probability. The name "Raviole Soaring" has been chosen because of th food speciality of the area: This regional speciality of the Dauphiné perfectly suits our ways of modern consumption: easy to prepare and quick to cook - only 1 minute!
Let's come back to the contest. 12 pilots from the area met around 10 am this morning and completed 4 round before the lunch in a strong wind (about 40 to 50 km) with some dust reaching 60 km/h. The slope is a grass field, with slow angle slope.
Then we had a lunch break of 1 hour to cook and eat some ravioles and other great specialities :) ! Then we started again for 4 additional rounds until 4 pm.
Yves Tirand won the competition with his Vampire. I got the fastest time with 41,72s. I thing this slope can go under 40s which is unbelivable when you see the angle of the slope. We were able at soem occasion to do some energy management turns. The slope was however most of the time very turbulent.
Here are the results
Yves : Vampire
Pierre : Alliaj HM
Laurent : Ceres F3F / Dynella
Arthur : Dingo
Olivier : Dingo
Serge : Dingo / Martinet
Thomas : Big Snip
Fabien : Freestyler 3
Stéphane : Sniper
Paul : Dingo
Joël : Caldera
Etienne : Ascot
A big thanks for the co-organizers for the food, the logistics, the pylon judges. We have a very friendly and breathy day !
I started the assembly of the Ambrosia F3X. First I prepared the wing servos wire and te equivalent in the fuselage. I use DIY plugs because you can make the exact length you need, and also because it is much cheaper. Ambrosia F3X has MPX green plugs housing already moulded.
With a mini drill, I prepared the housing on the fuselage ad let a lip all around in order to glue the plug in place.
The plug is fixed in place with cyanoacrylate glue. The result is perfect and clean
The Fuselage will be equiped with the MKS DS6125-H. The servos tray is cutted for futaba S3150, I guess, but not problem for the MKS servos.
In the wing, I will use 4 DS6125 equiped with their laser cut wood frames:
The servo hole is not that big, but the frame can enter with some exercice :) !
The glider servo family manfactured by MKS is expanding with 2 new versions of the already presented DS6125 wing servos.
The MKS DS6125-mini is a shorter version of the DS6125, still with impressive specs with its aluminium case and chrome gears: Torque is a little bit lower than the DS6125 but delivers plenty of power for glider application:
Dead band:0.001ms (Default)
Control System:+Pulse Width Control
Working frequence:1520μs / 333hz
(RX) Required Pulse:3.0~5.0 Volt Peak to Peak Square Wave
Operating Voltage:4.8~6.0 V DC Volts
Operating Temperature Range:-10 to + 60 Degree C
Operating Speed (4.8V): 0.12 sec/60° degrees at no load
Operating Speed (6V): 0.1 sec/60° dagrees at no load
Stall Torque (4.8V): 4.8 kg-cm ( 66.65oz/in)
Stall Torque (6V): 5.8 kg-cm (81.0 oz/in)
Motor Type: DC Motor
Potentiometer Drive: Direct Drive
Driver Type: FET
Bearing Type: Dual Ball Bearings
Gear Type: Chrome gear
Connector Wire Length: 15.0 cm (5.9 in)
Dimensions: 30x10x29.9 mm (1.1811X0.39X1.17 in)
Weight: 25.26g (0.89oz)
The MKS DS6125-H if the vertical mounting version of the DS6125 Mini, with the same specs expected the case shape.
So which servos for what glider application ?
The DS6125-H will be perfect as elevator servos. It will fit in the slimmest F3X fuselage, and if the servormances tests results are identical to its brother (excellent accuracy, positionning and low bending), will provide a crisp and solid control without any slope of the elevators.
The DS6125-mini will be prefered for ailerons where the DS6125 will be used for flaps or for large ailerons when needed. For example on a 4 m large sailplane, the DS6125 will be perfect.
MKS is well known in the helicopter world for the quality of their servos. I bet that it will be soon the same in the glider world !!!!
DS6125, DS6125-mini and DS6125-H servos are my choice for my next planes.