HWR MKII Posted February 3, 2006 Share Posted February 3, 2006 Wow the airbrush is working out even better than i thought it would for the weight saving. Keep it up! Quote Link to comment Share on other sites More sharing options...
IAD Posted February 4, 2006 Share Posted February 4, 2006 (edited) Surprisingly productive day. http://www.rcgroups.com/forums/showpost.ph...7&postcount=391 I really like the Tamiya gold..! ~Luke Edited February 4, 2006 by IAD Quote Link to comment Share on other sites More sharing options...
Shmitty Posted February 7, 2006 Share Posted February 7, 2006 This project amazes me more everytime I see new developments. Thanks for showing us all the progress! Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 9, 2006 Share Posted February 9, 2006 So how is the progress coming Luke? I cant wait to see this new one in flight with ALL of those control surfaces working. Quote Link to comment Share on other sites More sharing options...
IAD Posted February 10, 2006 Share Posted February 10, 2006 Things were a bit busy for me this week, so I haven't gotten much done. I'm going to install the fans today, and do some thrust-testing, comparing the results to a reference fan running in free air. My research suggests I should see a loss of about one ounce of thrust per fan, installed in the ducting. (~8 oz. total thrust, after ducting losses.) If I see a considerably more than that, I may need to cut 'cheater holes' just forwards of the fan, to improve air feed. These would be placed in the inner sides of the intake boxes, to minimize damage to the scale appearance. ~Luke Quote Link to comment Share on other sites More sharing options...
IAD Posted February 10, 2006 Share Posted February 10, 2006 [insert Beethoven's Fifth Symphony theme here...] I just got back from thrust-testing. I'm going to be doing some serious modifications to the ducting. I'm getting 4.5 oz. of thrust... TOTAL. :0 I tried the cheater-hole idea, which actually reduced thrust. I'm speculating it introduced a large amount of turbulence in the duct, reducing the effective intake area... Obviously, not good. This means I have to pop the bottom off most of the plane, fiddle with the ducting, and then put it all back together. I'm hoping it's something simple. (Right now, the prime culprit is the intake side is starving the fans.) I'll probably end up refinishing the ductwork, as well. I'll shoot for glass-like surfacing. Anyhow, that's a bit of a setback. ~Luke Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 10, 2006 Share Posted February 10, 2006 Well that stinks. Any ideas of what youll do to correct this one? Quote Link to comment Share on other sites More sharing options...
IAD Posted February 11, 2006 Share Posted February 11, 2006 (edited) After some simple measurements, I found the problem, and formulated a way to correct it. First, the problem: The exhaust ducting diameter is about 2-3mm too small. This is, to say the least, bad. (The current cross-sectional area is only 85% of what it should be.) The fix: Using 150 grit sandpaper on a dowel, I'm going to enlarge the foam duct until it's over-sized by about 2 mm. I will then construct new ducts from transparency material, sized to have the correct taper (just like on the first SV) and insert these into the enlarged foam ducting. This will save me the nasty task of having to re-surface the assembled ducts, which are pretty inaccessible. ~Luke P.S. I tested the 'starved fan' theory, by carefully removing the intake boxes, and the thrust didn't improve at all. In fact, the thrust went down a bit, indicating that while the intakes may not be perfect, they are definitely beneficial. So, for the time being, I'm leaving them alone. Edited February 11, 2006 by IAD Quote Link to comment Share on other sites More sharing options...
IAD Posted February 12, 2006 Share Posted February 12, 2006 Good news! I finished modifications on the left-side ducting, and.... I'm up to 3.125 oz. of thrust per fan! (That's quite a bit better than 2.25 per!) Note that it's also better than the fan running in free air without the intake lip, which suggests my ducting is at least somewhat effective. If I removed the intake box, I lost a good deal (~0.5 oz.) of thrust. Likewise, if I removed the 40mm-38mm cone on the exhaust, I lost ~0.2 oz... The fans seem very sensitive to ducting changes. Anyhow, now all I have to do is pull off the modifications on the other side, and this whole rotten 'thrustless' episode will be behind me. ~Luke Quote Link to comment Share on other sites More sharing options...
chrono Posted February 12, 2006 Share Posted February 12, 2006 Great news that it was so easy a fix! Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 12, 2006 Share Posted February 12, 2006 (Mr Burns voice) Excellent. Quote Link to comment Share on other sites More sharing options...
IAD Posted February 16, 2006 Share Posted February 16, 2006 Yes, very. I've pretty much finished both sides now. I'm going to add the saw-tooth on the intake lip, and make sure that doesn't kill thrust, and then it's time to glue everything back together. Then it's controls, then battery mounting and paint touchup, and then... DIE, CF VF-0! ~Luke Quote Link to comment Share on other sites More sharing options...
chrono Posted February 16, 2006 Share Posted February 16, 2006 After which we expect plenty of vids showing well earned crys of childish joy! Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 16, 2006 Share Posted February 16, 2006 I hope it all goes really well Luke. Hey guys i bet he pulls a cobra and a backflip on its maiden flight. Quote Link to comment Share on other sites More sharing options...
IAD Posted February 18, 2006 Share Posted February 18, 2006 (edited) I have been known to execute advanced maneuvers on the maiden, but on this airframe? I think I'm going to hold off until I'm sure of what it can do... A loop, a roll, perhaps... But no Z-IAS* moves. ~Luke *Zero Indicated Airspeed. I think that's a real acronym. Edited February 18, 2006 by IAD Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 18, 2006 Share Posted February 18, 2006 I didnt mean you would go out and intentionally pull those moves. I was speaking more of by accident. This new airframe has way more control surfaces than the balsa prototype and it seems it will have better thrust to weight as well by the time your done with it. Quote Link to comment Share on other sites More sharing options...
IAD Posted February 18, 2006 Share Posted February 18, 2006 Ohhhhh! Well, then. Yes. I can't say that it isn't a possibility 'something' interesting will happen. As long as I'm in control when my altitude is 0.0 ft, I'll be happy. ~Luke Quote Link to comment Share on other sites More sharing options...
IAD Posted February 18, 2006 Share Posted February 18, 2006 http://www.rcgroups.com/forums/showpost.ph...8&postcount=422 Latest post on RC-G... Working out some of the more fiddly bits on the control system. ~Luke Quote Link to comment Share on other sites More sharing options...
IAD Posted February 22, 2006 Share Posted February 22, 2006 Latest update, from RC-G: "Well! How does 6 oz. of thrust sound..? With thrust-vector vanes. (Fully charged battery. Just before the BEC kicks in, I get ~4.25 oz..) I did some more experiments, and found that there's a very specific spread position at which things work well with the TV vanes. Adding a discontinuity on the inner surface didn't really seem to do anything... I'll keep playing around with it, though... ...There are still some losses, I think I'd be looking at 7 oz., without the TV system, but... Win some, loose some. I may yet be able to improve the vanes further, but... 6 oz. should keep a 12.8 oz., 9.2 oz./ft^2 ship in the air... Hopefully. ~Luke" Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted February 23, 2006 Share Posted February 23, 2006 how is the ratio on this one compared to the balsa prototype. If that one could fly than the new one will have no problem. Quote Link to comment Share on other sites More sharing options...
IAD Posted February 23, 2006 Share Posted February 23, 2006 In the end, the thrust-weight ratio is almost identical. (The new one is 1:2.13 T:W, the old one 1:2.28.) Some slight improvement. The thrust-vector losses weren't present in the older version, because they were mounted further out from the exhaust duct. This isn't an option on the new ship, because of space restrictions. However, because of the considerable loss of weight, (3 oz.) the wing-loading of the new version is much better, which should make it easier to fly, while at the same time requiring less power to remain in the air. If I decide to use a different battery pack I have my eye on (better voltage under load, less weight, but less capacity) my AUW would go down to 11.3 oz., for a 1:1.83 T:W ratio, with an even lower wing-loading. The further reduction in power requirements would help to offset the loss in capacity. Options, options. ~Luke P.S. Just to make this even more confusing, I understand that a better prediction of performance can be made based on power loading. (W/lb.) If this is true: Old ship: 100 W/lb. New ship: 125 W/lb. Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted March 3, 2006 Share Posted March 3, 2006 I know things are busy but how are you coming along on flight tests? Quote Link to comment Share on other sites More sharing options...
IAD Posted March 3, 2006 Share Posted March 3, 2006 I know things are busy but how are you coming along on flight tests? 375841[/snapback] No flights yet... I started hooking up the canards, and figuring out the best way to tie them into the control system... The battery mounting is in place, and tomorrow afternoon, I'll start up a weekend's worth of control system installations. Tricky business, getting everything to go in the right directions, off a mere two servos. (This is what I looked like, after designing the final linkage setup: ) ~Luke Quote Link to comment Share on other sites More sharing options...
IAD Posted March 5, 2006 Share Posted March 5, 2006 Got a good deal of work done today... The canards are online, the elevators are installed and functional... Thrust-vector interconnects, and elevons are all that are left. (And weathering/panel-lining, which will be done after it flies.) ~Luke Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted March 5, 2006 Share Posted March 5, 2006 Cool . Anymore airframe mods discovered yet or will they rear their ugly heads on the test flight? Quote Link to comment Share on other sites More sharing options...
IAD Posted March 5, 2006 Share Posted March 5, 2006 At this point, the only way to know if additional modifications will be necessary is to test-fly. (STRESS!!! ) ~Luke Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted March 5, 2006 Share Posted March 5, 2006 May she fly straight and true. Quote Link to comment Share on other sites More sharing options...
IAD Posted March 5, 2006 Share Posted March 5, 2006 Thanks! First flights next weekend, hopefully. (Nice avatar!) ~Luke Quote Link to comment Share on other sites More sharing options...
e_jacob77 Posted March 15, 2006 Share Posted March 15, 2006 (edited) Hi all, How was the test flight????? edit: Forgot to ask what scale the Ivanov version is in?? Edited March 15, 2006 by e_jacob77 Quote Link to comment Share on other sites More sharing options...
IAD Posted March 18, 2006 Share Posted March 18, 2006 I haven't flown yet... Still working on the last few control system details, and waiting for some decent weather. The scale is.... Oh... 1:25th... (3' long.) ~Luke Quote Link to comment Share on other sites More sharing options...
IAD Posted March 18, 2006 Share Posted March 18, 2006 Decided to build a center-of-gravity test-bed. Better to smash up some sheet foam and a day's worth of work, rather than the real thing. http://www.rcgroups.com/forums/showthread....=31#post5200153 ~Luke Quote Link to comment Share on other sites More sharing options...
NoSuchFile Posted March 18, 2006 Share Posted March 18, 2006 Decided to build a center-of-gravity test-bed. Better to smash up some sheet foam and a day's worth of work, rather than the real thing. http://www.rcgroups.com/forums/showthread....=31#post5200153 ~Luke 381656[/snapback] Hey this looks way funny, hopefully we can se the results of those tests lol Quote Link to comment Share on other sites More sharing options...
HWR MKII Posted March 18, 2006 Share Posted March 18, 2006 Luke you could always make precut gliders too Im glad the test rig balance affirmed your previous estimates. Quote Link to comment Share on other sites More sharing options...
IAD Posted March 19, 2006 Share Posted March 19, 2006 Yes, I was rather pleased. Right now, it's actually got some basic controls, but the wind is so strong, I've only been able to fly for a couple seconds at a time, between gusts. NoSuchFile: Whaddya mean, looks funny? It looks like an SV-51... Which... Well.. Ok, fine. SVs do look funny. Too many fins, and a Cyrano-de-Bergerac-esque nose. ~Luke Quote Link to comment Share on other sites More sharing options...
NoSuchFile Posted March 19, 2006 Share Posted March 19, 2006 Yes, I was rather pleased. Right now, it's actually got some basic controls, but the wind is so strong, I've only been able to fly for a couple seconds at a time, between gusts. NoSuchFile: Whaddya mean, looks funny? It looks like an SV-51... Which... Well.. Ok, fine. SVs do look funny. Too many fins, and a Cyrano-de-Bergerac-esque nose. ~Luke 381768[/snapback] I meant the prospect of having fun smaching the foam version Don't get me wrong, i hope it flies well and proves the bigger/better version will fly and be able to do awsome maneuvers, but still, it'd be fun to use it for crashes lol Quote Link to comment Share on other sites More sharing options...
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