McG 6969 Posted November 4, 2017 Author Share Posted November 4, 2017 Hello to anybody still out there, I went on with the firewall preparation, drilling the motormount holes and having the holes in the foam doubler done, but also to realize that I’m missing some precious bits for the powertrain. I already have a 2S 850 mAh, but missing some thingies like motor, battery and ESC connectors. In fact, my decision to build the ChtiCat for the approaching indoor season was some kind of ‘improvised’, so some bits are still somewhere on the slow boat from Shenzhen… I have a DSMX 6210 receiver together with it’s remote sat, but it’s way too large to enter that small tapering aft deck. Anyway, for the sake of recording some progression, I scored the inside of the deck with an (empty) ball pen. And, here’s the back of the firewall with some ply roundels for the motor screws to have a steadier grab. The intention is to keep the original 3° upthrust, but you never know if one should have to add some washers when building in the ‘nearly darkness’… Hakuna matata Chris BRU - BE / CTR Bits Control Quote Link to comment Share on other sites More sharing options...
Max Z Posted November 5, 2017 Share Posted November 5, 2017 I am still out here Chris. You have inspired me to design and build this: Carry on, Max. Edited By Max Z on 05/11/2017 11:53:49 Quote Link to comment Share on other sites More sharing options...
AndyD Posted November 5, 2017 Share Posted November 5, 2017 still watching. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 5, 2017 Author Share Posted November 5, 2017 Aah... that looks really 'fun', Max. Did you have a maiden 'glide' already? I'm trying to find out your 'motion principles', but not that easy without details... Let's have a guess. I see a double bottom thickness, so it could be that the lowest one is just the contour edge creating a space for a air cushion. That is, if the prop is blowing into your quarter circular fuse right through the top bottom plate... also your high aft fuse & fin could indicate a hovering design... All fine guesses, but I don't see a rudder? Don't tell me that your motor is mounted on a servo plate panning left or right to get some 'turning' thrust... I won't give any comment regarding your 'Dolle Mina'... Hakuna matata Chris BRU - BE / CTR #5 Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 5, 2017 Author Share Posted November 5, 2017 Thank you, Andy. Always nice to have a visitor. I just hope the itchy fingers are still bearable... Hakuna matata Chris BRU - BE / CTR Itch Control Quote Link to comment Share on other sites More sharing options...
Max Z Posted November 5, 2017 Share Posted November 5, 2017 Posted by McG 6969 on 05/11/2017 12:33:30: Aah... that looks really 'fun', Max. Did you have a maiden 'glide' already? I'm trying to find out your 'motion principles', but not that easy without details... Let's have a guess. I see a double bottom thickness, so it could be that the lowest one is just the contour edge creating a space for a air cushion. That is, if the prop is blowing into your quarter circular fuse right through the top bottom plate... also your high aft fuse & fin could indicate a hovering design... All fine guesses, but I don't see a rudder? Don't tell me that your motor is mounted on a servo plate panning left or right to get some 'turning' thrust... I won't give any comment regarding your 'Dolle Mina'... Hakuna matata Chris BRU - BE / CTR #5 Control Yes Chris, i made some test drives in the house and at our clubhouse, and it goes very well and is fast. I did not dare to open the throttle fully, too many obstacles (tables and chairs). It is a regular "Aéroglisseur", the prop blows into the inlet behind it, and creates an air cushion below. The lowest layer of depron is cut out in the middle for that purpose. I don't understand what you mean with "your high aft fuse & fin could indicate a hovering design..." The motor indeed pivots on top of a servo/receiver/esc combination, THIS unit. Control is with a Graupner MZ-4 which was specially developed for this unit, but it can also be a regular HOTT transmitter. My pilot feels offended, he feels he is definitely masculin. But you never know these days..... Max. Quote Link to comment Share on other sites More sharing options...
AndyD Posted November 5, 2017 Share Posted November 5, 2017 Hi Chris as winter zooms closer you could do a build blog on one of these for out side use,looks nice and cheap. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 5, 2017 Author Share Posted November 5, 2017 Yep, I saw the Ice Racer somewhere on a French forum, Andy. A real fun thingie as well, except that the last time we had some snow here around BRU was three years ago ad the next morning it was already gone... But "cheap", don't know. It's made in Germany by Sebald-Modellbau. The birch 3mm kit costs €49 & shipping to EU is nearly €17. Add a 1000KV motor, ESC, prop, some hardware & a few 3S Lipos... and just make the total. Also funny enough, the CNC cut formers for the bottles use the dimensions of a brand of water only available in Germany... I think my Chticat Racer will be around (less than?) €50, but ALL in... But the Ice Racer remains a very fun concept anyhow. Hakuna matata Chris BRU - BE / CTR Water Bottle Control Edited By McG 6969 on 05/11/2017 17:56:02 Quote Link to comment Share on other sites More sharing options...
AndyD Posted November 5, 2017 Share Posted November 5, 2017 didn't realise it was a kit,€49 ouch,i design my own,well after sorting all the other projects. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 6, 2017 Author Share Posted November 6, 2017 Indeed, sometimes it's even more fun to design and build your own version, Andy. But don't let your ChtiCat get too much down the queue, it could bite your 'itchy' fingers... Hakuna matata Chris BRU - BE / CTR Bite Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 6, 2017 Author Share Posted November 6, 2017 Hi again, While waiting for the small electrical bits to arrive, I still have enough to take care about. I covered the acetate thrust fairing with some yellow laminating film to have it ready to be glued in. I fact, as the ChtiCat is a small thingie, I’m going to use some cut-offs from the Ballerina deco scheme. Gaston insisted to have a dry fit of the bits available so far. I was surprised that, when curved, the acetate is really steardy, stronger than 3mm Depron would be anyway. Also the reduced thickness seems to be a nice advantage to fit it nicely against both sides. Next step will be to create an additional small square former, half way between the front and the top deck with a concave cut out for the fairing. Allowing less torsion of the front end will (hopefully) avoid Don’s kind of ‘destruction’. I also did laminate the small vertical mount after giving it a quick LE rounding. If you have a closer look, the LE of the top deck received a thin 6mm strip cut out of a tongue depressor. Getting ready to stick all those bits together now. Hakuna matata Chris BRU - BE / CTR Bits #2 Control Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 6, 2017 Share Posted November 6, 2017 McG, sorry not been following post. Mine runs on a HobbyKing Donkey motor/controller. Runs on a 3s 800 battery. Prop is as big as you dare, pitch is as big as you dare. You need huge exponential, as it corners in a controlled skid. You watch the skirt, they can flip, and you try to run them just below flip point in the turns. Don't shut the throttle, no aerodynamics with no throttle. Don't open the throttle, they flip in the corners. And they are at least 3 times faster than anything that flies in the hall. Collisions are frequent, as they all are in one plane. Mine was destroyed last Sunday. Enjoy. Hint, the battery MUST BE LOCATED IN THE TUNNEL BEHIND THE MOTOR. Failure to do this will cause excessive flipping. Don't know why. Edited By Don Fry on 06/11/2017 19:07:24 Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 7, 2017 Author Share Posted November 7, 2017 Thanks for visiting and for your advises, Don. That HK Donkey Combo looks like a very nice solution and it even follows the 2204 motor/10A ESC race regulations. Are you using the 1700KV version? Thank you regarding the battery location, my intention is indeed to have it on top of the ESC on a tray just behind the firewall. I'm using a XXD 2212 as I already had a few of those and they were very cheap at €4,80/piece... But now I'm getting a bit worried as the max power of a 2204 on 3S is just under 100W and the 2212 gives around 95W on 2S, up to 170W with a 3S Lipo. I expect my 'thingie' to weight around 200gr, say 250gr with a 2S 850mAh... So on 2S, I will be around 190 W/lb ! Of course it's not an airplane... but, am I building a 'dragster' then? As I am really inexperienced, the first purpose to build the ChtiCat was to get some Tx sticks practice during the winter months... Well, maybe I should build a second glider right away... Hakuna matata Chris BRU - BE / CTR Watts (What's) Control Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 7, 2017 Share Posted November 7, 2017 Chris, Yes I use the 1700KV unit. It is robust, and good value. I have just weighed my debris, and it's 225 grams with its 800 3s battery. It has a 7 by 4 prop, which is good for the basketball court sized gym my club uses. You balance accelatation to top speed, and slowing it again into the corners, as you slow it by reducing the throttle, not closing it. Close the throttle, equals no control. Another tuning modification, is changing the size of the Velcro pieces on the bottom. It has the effect of changing the centre of grip, so you can balance it in the turns, as it drives like an old fashioned Porche 911, and swaps ends if provoked. Remember, winners are first past the line, not the fastest. I might suggest you make a sacrificial foam bumper , velcroed on, to go on the front end. The front end has a hard time, and any reduction of g force in a crash is good. It will sharpen you, 5 minutes and my eyes dry out, no time to blink. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 7, 2017 Author Share Posted November 7, 2017 Hi Don, It's really great to receive some feedback when one gets a bit into trouble. So thanks a lot for it. I guess I wasn't to far away with my 'guestimate' of 250gr then. The 2212 is about 20gr heavier and I'm planning to laminate the beast with 40 micron vinyl. That could come very close. I'm taking good note of your handling procedures and I'll start to invest in Velcro strips as I've raced 911s in a former life. So, I see what you mean... An emergency foam bumper sounds like a very welcomed idea as well. Thanks again Hakuna matata Chris BRU - BE / CTR Velcro Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 8, 2017 Author Share Posted November 8, 2017 Hi to all, A large 'cloud of flue' seems to be covering the area here and with some fever handicap, I had to cancel my visit to La Grotte today. I've been making some (little) progress with the scheme markings though and they are nearly finalized now. I have some question for the Leccy Gurus. I've been reading quite often that attention should be given not to increase the length of the wiring between battery and ESC, giving a preference to lengthening the wires from the speed controller to the motor. Right? My problem with the ChtiCat is the other way around due to the lack of available space. So, is there a problem making the motor/ESC wires shorter? I would have thought "No" as the resistance of the wires will only get lower, but I prefer to ask before committing. Any advice, please. Hakuna matata Chris BRU - BE / CTR Ohm Control Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 8, 2017 Share Posted November 8, 2017 No. But re making it pretty, these things have a really hard life. A nasty trick Is to corner inside a victim. And because there is a victim to lean on, you can open it up coming out of a bend. Victim ends up in the wall. Newton's laws rule. Remedy is a judicious lifting of throttle. Then the aggressor understeers across your front, then swaps ends trying to get grip before hitting the wall. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 9, 2017 Author Share Posted November 9, 2017 Thanks again, Don. I'll cut the ESC wires to the appropriate length as soon as I receive my connectors. Concerning "making it pretty", I'm convinced a ChtiCat can have a really hard life, but then on the other end, I can't imagine sending a brave soldier naked to the front line, especially if it's a 'kamikaze' mission... As for victims to lean on or getting assaulted by other beasts, chances are pretty non existing. I presume I will be just by myself with the thingie. But then, the real danger will be when the walls decide to start crossing my intended track... Hakuna matata Chris BRU - BE / CTR Track Control Edited By McG 6969 on 09/11/2017 09:55:09 Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 9, 2017 Share Posted November 9, 2017 You will not make it to General then. Edited By Don Fry on 09/11/2017 12:32:22 Quote Link to comment Share on other sites More sharing options...
Iris Vlieghe Posted November 9, 2017 Share Posted November 9, 2017 My eyes love the 'pretty' part. Maybe I am shallow? I am not 'technical', that I know. So all I can say about this 'machine' is whether I think it's pretty or not. So keep on working on the pretty part too. You may not make it to General but you will be forever my Captain. Ay ay sir! - Iris BRU - BE /Aesthetics control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 10, 2017 Author Share Posted November 10, 2017 Thanks both , I had a large smile reading your comments. I'll probably never make it to General, Don... ... or maybe not even to The LotH's Captain... ... but then, I'll stick to "Saving Private Chris"... Hopefully I can get back to La Grotte today, but the connectors didn't show up yet. Hakuna matata Chris BRU - BE / CTR Rank Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 14, 2017 Author Share Posted November 14, 2017 Hello everybody, I managed to get to La Grotte again and could finally resume the ChtiCat build. While having some spare ‘virus’-time, I started pondering (slowly) about the rudder design of the thingie. It seems obvious now that the fastest air movement is located at the inclined extractor part. Well it seems that the designer made the rudder less reactive - with a rounded off bottom part - precisely at that area. So, I decided to increase the rudder width by 10mm (+/- 18%). The white foam part in the pic. Then I changed my mind by having a smaller width at the top and a larger one at the bottom. The yellow/fluo laminated rudder. It looks a bit like a gentle 3D beast now. As the rudder hinge will be a simple clear strip of lamination it’s easy enough to change it later on if needed. As I wrote before and as the fin already shows, intensive use of the Ballerina vinyl off-cuts is the motto here. I also prepared the battery tray - ie foam laminated with acetate - behind the motor mount with a space underneath to receive the speed controller. Only a dry fit shown here. The other good news is that I also received the missing little bits including the Lipo & ESC connectors. Hopefully I can have some better progress from now on. Hakuna matata Chris BRU - BE / CTR Virus Control Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 15, 2017 Author Share Posted November 15, 2017 Hi again, I made a start right away at getting those tiny connectors out of their bags and got the soldering equipment out of the drawer… After some really disastrous first results, I quickly switched to measuring and cutting some vinyl lamination and progressed with sticking that to the ChtiCat as I experienced the pleasure of a lot more success. Unfortunately, I forgot the camera at La Grotte - I suspect that happened before during the Ballerina build - but I officially promise to post a lot of them (say?) tomorrow… Hakuna matata Chris BRU - BE / CTR Pic Machine Control Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 15, 2017 Share Posted November 15, 2017 Chris, I admit I have consumed a fine Bordeaux with my dinner of lapin aux prunaux. But, regarding the rudder, this is the fastest thing in the hall. If a plane is airborne, you are travelling at at least twice as fast, and that is in the corners. And it has a huge rudder, to give some control when it accelerates from zero, but once running the rudder throw is small. So you program big exponential. Mine is iro 50 60 %. Don't over think these things, I don't know if I will rebuild, build another. My hall, a basketball court is challenging. If it was bigger, I would enjoy tuning it. But running them is a brutal war game. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 16, 2017 Author Share Posted November 16, 2017 Hi Don, Well, The LotH and I shared a 'Plateau de Fromages' and a - too small - Spanish Epulum Gran Reserva 2009... Regarding the rudder mod, I'm just trying to find out if it would give a better response at 'low' speed - or not... and yes, I'm convinced a lot of expo will be needed at higher speed. I still have to learn how to bind and configure my old Tx. I guess I will be crying for help around here quite soon now. And later on, I can already project a very suicidal 'maiden glide'... Hakuna matata Chris BRU - BE / CTR Expo Control Quote Link to comment Share on other sites More sharing options...
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