RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 [quote]ORIGINAL: udet1918 Holy Cow! What does it weigh? Ron [/quote] Won't know till everything is cut away. Some where around 22#'s. Much less than someone had calculated 60#'s. One thing for sure the damn thing won't break ! [/quote] I my defense ( I estimated weight) I thought all pieces were 1/2" thick, included the weight of the adjacent bulkheads, and didn't account for the lightening pattern. Make sure the bolts are strong enough. Two plates make a good imitation of shears for undersize/not enough bolts.
Posted on: 8/23/2009 8:14 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9037428

RE: 1/8th scale B-1B
What kind of spar's going to be at the root of the wing panels?
Posted on: 8/3/2009 4:19 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8986802

RE: Loading and CG
Most modern airliners built since the 80s can measure the weight on each landing gear. If you can do that, you (or the flight computer) can calculate the CG location. - I have been bumped from a flight before (on an old 727) that left with empty seats due to CG considerations.-
Posted on: 7/29/2009 9:48 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8973321

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 John I will let you do any analysis you want . Just let me know what info you need. Butch [/quote] No sour grapes there Butch, just an observation. If you wanted to do an analysis of the same thing made from 1/4 plate, we could take a look. At 1/2 inch, there is no reason to. It's strong as a bridge, but they don't have to fly :) I'll see if I can get that old PC started for the CG work.
Posted on: 7/14/2009 9:41 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8934051

RE: 1/8th scale B-1B
[quote]ORIGINAL: mr_matt I would be curious what that gear will do at 245 pounds at maybe a 2-3 g hard landing?. Very complex and trying to figure all of the loads paths... [/quote] That's a good point. The wings might lift it, but the poor gear. That's a pretty good argument for weight management. [quote] Good thing they are going pure TLAR! Great project and a great group of guys. [/quote] I offered to do some analysis of the spar (actually recruited a FEM analyst to help). I guess he went with 1/2" plate instead. I was gonna do stability analysis(CG location) as well, can't find the one I did for another B-1 on this PC. Might have to fire up the ancient PC to get it.
Posted on: 7/14/2009 7:41 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8933636

RE: 1/8th scale B-1B
[quote]ORIGINAL: mr_matt [quote]ORIGINAL: Johng 245 lbs [/quote] I am actually with you John, on the current trajectory I think it would get to 250. But I think there will be a mid course correction :-) [/quote] Is that your bet, cause I would be tempted to revise upwards if you were out-bidding me. [;)] But these folks that are below 200 just ain't getting it, unless Butch has dropped
Posted on: 7/14/2009 5:33 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8933292

RE: 1/8th scale B-1B
245 lbs
Posted on: 7/14/2009 6:41 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8931666

RE: 1/8th scale B-1B
PM'n you Dean
Posted on: 7/10/2009 1:56 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8921960

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 CG Chart for the real plane. The MAC moves with the wing sweep, so the CG on the model will only change about 1% . Not worth worring about as everyone has said. [/quote] Hey Butch: Your chart jogged my memory about an article a read years ago about the stability of the B-1. It has a control system that limited the max angle of attack/ Lift cooefficient as it would experience pitch-up near stall, like a tail heavy F-18, depending on the load-out. Makes sense with the broad arrow shape of the forward fuse. That's what I remember from the article anyway. Just didn't want you to try to match the flight manual CG and think it would all be good. I'm sure you were gonna go with a conservative forward CG location anyway. I may have figured out CG location for someone doing a smaller B-1 some years ago. If you want a recommendation, I'll look up the file. I did it in a spreadsheet & could convert to this beast easily.
Posted on: 7/7/2009 3:19 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8913849

RE: 1/8th scale B-1B
Yeah, that's gonna be 60 lbs or so. I like the bolt-in feature. Maintainable...
Posted on: 7/4/2009 12:38 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8905939

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 If it is that heavy I will have to put some lighting holes in it. The bulkheads will be 1/4''. That section of the plane has the wings and landing gear that it has to support. It won't have 1/8'' balsa stingers. We are going to build one for testing till destruction. I'm hoping each side will support 1000# of concrete. If I get hurt I will post pictures ! Ha ! [/quote] Are there any vertical pieces that are 1/2 aluminum, or is it just the spar caps that are 1/2" If it's just spar caps and 1/4" bulkheads, the weight is more like 35-40 lb.
Posted on: 7/4/2009 12:50 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8905136

RE: 1/8th scale B-1B
[quote]ORIGINAL: erbroens As you are making a mockup of the wing pivot box to be later made in metal, why not making it arched, like the full size one? the advantage is that it will be stronger at its very center, and it will ''anchor'' the wing better in the fuselage, considering that that all the wing flight loads will be concentrated in this quite narrow box. Of course, this is a humble opinion! [;)] [/quote] Better to have it straight and stout. The bulkhead shape would resist bending moments well on paper, but would take complex analysis to make sure they wouldn't buckle. The srtaight carrythrough spar is a fine solution. 99% of airplanes flying have a straight spar thru the fuse. The bulkheads need to be stout in order to transfer the twisting loads of swept wings as well. BTW- a rough calc shows Butch's spar to weigh 60-70 lbs, before adding bearings & races, etc. [X(]
Posted on: 7/3/2009 4:20 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8904016

RE: Lanier Stinger plans
The stinger is a good flying design, but the fuselage needs some help. Specifically, the wing saddle (at least on the 120) notches down through the fuselage so far it's a weak spot. You either need to extend the plywood saddle doublers far past the next bulkhead, or better yet, leave the fuselage sides as planks, and mount the wings with a wing-tube set. The stock fuse will crack at the saddle on landing after some hours in the air... Other good mods; Oversize the rudder and elevator . When I built the 120, the elevator and rudder proportions were taken from the Ultimate Bipe. Last I looked, which was a long time ago, plastic and fiberglass turtledeck, cockpit canopy, and cowlings were all available at reasonable prices.
Posted on: 6/9/2009 9:48 PM by Author "Johng" in the forum "Scratch Building, Aircraft Design, 3D/CAD"
http://www.rcuniverse.com/forum/fb.asp?m=8839797

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 I wouldn't know how to do something like that. The only thing I could think of is put money in his Pay Pal account. I will put some money in there, but I have something at stake. Don't think you could get people to send money just for the hell of it. But if people are interested I will post his Pay Pal and let the "Video-thon" Begin ! [/quote] Sell buddy box time IOU's on the Bone for $10 a minute. Otherwise, that is a really good spar/bulkhead design. One thing that might save Bob some time, is that rectangular 6061 AL tubes are available commercially in the size and thickness range needed for that spar. http://www.metalsdepot.com/products/alum2.phtml?page=tube&LimAcc=$LimAcc&aident=
Posted on: 6/9/2009 9:35 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8839756

AR6000 long time to boot with dx6i
I got the AR6000 bound to the dx6i transmitter after a few tries. Took a long time for the bind process. As in, I started the bind, and walked around the house, to the fridge, etc with the tx in-hand waiting for the bind signal . It did after at least a minute. Now, I turn on the tx and then plug in the rx, and it takes at least 30 seconds for the connection to sync up. At first I thought the rx had become "un-bound", but it fiinally synced. Is that normal on this setup?
Posted on: 6/9/2009 7:37 AM by Author "Johng" in the forum "JR Radio & Spektrum Radios"
http://www.rcuniverse.com/forum/fb.asp?m=8837716

RE: Excess speed on landings
Good advice on throttle and props so far. If you can't kill the idle thrust, then it will be a problem on approach. One way to tell is: will the plane sit still at idle on pavement or does it start rolling as soon as you let it go? If you can't cut it back to a sitting idle, it's too much. If the motor won't idle down without dying, the idle mixture needs to be adjusted. It's probably too rich. See if it speeds up when you pinch the fuel line at idle throttle. If it speeds up and stays running for a few seconds after pinching the fuel line shut, you could lean out the idle mixture. That will allow you to slow the idle another click or two. Also, when the plane is on approach, are you aiming for the end of the runway, or right in front of yourself. You need to have the plane on a glideslope towards the end of the runway. If you are aiming for the spot in front of you, half the runway is gone before you even had a chance. Then when you flare out the plane carries even farther, pretty soon you are out of runway. I know this is a problem I had many years ago. Adjust your pattern down the runway. You could also just need a little more up trim. There's no guarantee the landing trim will be the same as flying trim. You could retrim manually. Or you could put a slight adjustment mixed on a switch.
Posted on: 5/25/2009 9:21 AM by Author "Johng" in the forum "Beginners"
http://www.rcuniverse.com/forum/fb.asp?m=8796496

RE: Pretty uncomfortable experience today...
gaRCfield: You helped a newbie out. That does not mean you are the instructor by default. You were the "trim guy" or maybe a very helpful spotter. The guy who lost his plane took responsibility for flying it solo. The crash is all on him. He took control of his plane and couldn't handle it. HighPlains gets +10 ITG points (internet tough guy) for the grounded comment. John [quote]ORIGINAL: HighPlains You watched him go from a high alitude to a crash in a gentle wide turn? You should be grounded for a couple of weeks to think about this. [/quote]
Posted on: 5/24/2009 12:13 PM by Author "Johng" in the forum "Beginners"
http://www.rcuniverse.com/forum/fb.asp?m=8794490

RE: 1/8th scale B-1B
I think Ron S is saying a lot of smart things here. To boil it down, combining the bulkhead shape with the function of the spar to resist bending probably is not the best approach. A carrythru spar of rectangular construction would handle bending and twist loads, and be easier and lighter to construct. A straight spar could also be bolted in and removed for maintenance or replacement without tearing the fuselage apart. If the wings are to sweep back, twisting loads must be considered. A box spar would help with that as well Tubular aluminum 6061 of rectangular cross section up to at least 6"x6" with varying thickness is commecially available in reasonable lengths. The ends could be milled to the needed shape and the whole beam would slide thru the fuselage and bolt to the fuselage bulkheads. Those bulkheads could then be built much lighter, although they would still need to deliver the twisting loads to the fuselage skin. I also have been thinking that there should be some sort of fuselage keel system to enhance longitudinal strength. It does not need to be on the centerline, but perhaps vertical supports along the sidewalls of the bomb-bays should be built as integrated stiffeners.
Posted on: 5/18/2009 9:46 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8778521

RE: RAMTECH FAN
The dynamax i have I'm going to hold onto for possible e-conversion. I do have some nitro motors & pipes that I'd be willing to let go very reasonably. I have a OS 91 with ceramic bearings and new performance piston set - haasn't been run since I put the new parts on. Also have a OS 77, and a handfull of K&B 1.0's, Have a Rossi df parts motor and a pipe for Byrons fan use. I also have one or two Macs pipes for the K&B 1.0. Anyone interested PM me...
Posted on: 5/5/2009 11:44 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8742536

RE: RAMTECH FAN
Another pic
Posted on: 5/2/2009 8:18 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8733839

RE: RAMTECH FAN
Ralph: The fan is new and unused, but the box has been around long enough that it's a bit tired ( just the box that is). The box set is for a K&B 1.0 motor, which I think just means it has a shorter spool on the rotor. I also have the long spool, which should be for the OS. I only put one DF unit together in a plane, and that was like 10 years ago. And it was a K&B. So, take a look at the pics and tell me if this is what you need.
Posted on: 5/2/2009 7:50 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8733801

RE: RAMTECH FAN
I can probably find a NIB one in my shop. Lemme check after work.
Posted on: 5/1/2009 7:17 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8731124

RE: Mythbusters
Do a google search on the old Glenview NAS outside Chicago. It's probably a foreshadowing of what will happen with Alameda. It was a model aircraft mecca as the old nationals (I think) were hosted there for years. Plus all the training that went on there for WW2 thru the end of the century. I saw my first airshow there in the mid-'70's. I was still small enough to be carried by Dad. Probably one of the first showings of the F-14, but I remember it clearly. The show consisted of a flightline of pretty much every frontline jet in the navy taking turns zooming around the pattern, doing speed runs and touch & go's. All through my childhood I remember the hum of C-130's and P-3s as we lived about 10 miles from there. Now the place is McMall/McMansion development. One of those fakey "town-center" things. They saved the base ops center as a historic building and sits at the end of the mall's cul-de-sac. At least there's some nod given to the history there.
Posted on: 4/30/2009 1:57 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8729185

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 Don't be so sensitive, Battery operated toy are for "Girls". Really I have seen a lot of them ! [:)] And the thought of a "Byron Fan" makes me shiver. Besides they run backwards. Butch [/quote] Man you are going to be disappointed when I fly that old U-2 you molded; on an e-dynamax conversion. [:D] Not being sensitive, just cynical at all these folks that [i]'think'[/i] they know what they are talking about. You should take a look around at the conversions that are being done with 5 and 6" fans. Pretty sure BV would argue about electrics, since his demo trailer is now full of them.
Posted on: 3/12/2009 11:07 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8570102

RE: 1/8th scale B-1B
[quote]ORIGINAL: Mike Emilio [quote]ORIGINAL: Johng Also, no reason this couldn't be a EDF. 4x E-byron fans = 60 lbs thrust. [/quote] Somehow, , , hmmmm, , , , I just don't see squeelin' electrics doing this project justice. Not to mention a ton in battery weight that never goes away. [/quote] You guys are obviously the experts. I'm just a rocket surgeon. Obviously, I should
Posted on: 3/12/2009 8:09 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8569668

RE: 1/8th scale B-1B
The fact that they do that makes the crew feel a lot less like they are sitting in a pickup truck on a bad road.
Posted on: 3/11/2009 2:31 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8567197

RE: 1/8th scale B-1B
[quote]ORIGINAL: causeitflies [quote]ORIGINAL: Johng Yes, if you have an air-data computer, that can sense the gust when it passes the nose, compute the response, and send it to the canards before the gust makes it to the wing - they would help soften the fuselage stress. That's what I meant by ride-smoothers. I doubt even eagletree can give you that feature though. [/quote] That's
Posted on: 3/11/2009 2:00 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8567119

RE: 1/8th scale B-1B
Yes, if you have an air-data computer, that can sense the gust when it passes the nose, compute the response, and send it to the canards before the gust makes it to the wing - they would help soften the fuselage stress. That's what I meant by ride-smoothers. I doubt even eagletree can give you that feature though.
Posted on: 3/11/2009 1:49 PM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8567076

RE: 1/8th scale B-1B
[quote]ORIGINAL: Hustler58 It will probably have everything except Variable-aspect engine intake ramps. Not needed on the model and a real pain to build. [/quote] No reason to have the front canards active either. They aren't flight controls, just 'ride smoothers' on the real thing. Might as well hard-mount them. Also, no reason this couldn't be a EDF. 4x E-byron fans = 60 lbs thrust.
Posted on: 3/11/2009 7:57 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8566078

RE: Dean Lassek A-10 - from the bottom
[quote]ORIGINAL: cgrcjet [quote]ORIGINAL: I_Fly_Coolers Congrats on the maiden flight cgrcjet !! I am thinking along the same lines as John, lighter weight, less power. I think the kit built GM A-10 over at RCG may be over-powered and therefore over-weighted...A lightweight setup with a pair of 90mm midi fans on 8S would be more than enough for a Hog of this size.. And..yes, start your own thread..the amount of work you have done certainly deserves the attention [;)] [/quote] I know. I am trying to lighten up the layup schedule. It seems if even at that i would only loose maybe a couple of pounds at the most maybe less. I just purchased a couple rolls of 2.4 and 3.7 oz. cloth. If i remember right i think the whole airframe came in at about 11-12 lbs. Open to any suggestions on layup schedule. I should be able to get it down to at least 17-20 lbs fly weight. Dean? [/quote] Weight loss : THe place to loose weight is in the heaviest parts first. If you save 10% off a heavy part you are doing alot better than saving 10% off a lighter part. And it's usually easier to find fat on the heavier parts. As an engineer that used to work in light aircraft production, the heavy bits are the motor, landing gear, and avionics in order. If you take the motor and landing gear off a 4 seat general aviation plane, 3 strong guys can pick up the rest and move it. You quote a flying weight of 24 lbs. 2 lbs for each fan assembly and 6 lbs of batteries means that power accounts for 10 lbs of the total. In other words, your airframe weight minus power is 14 lbs. I think 26 lbs of thrust is well overkill on a plane of this type. You won't get down to 17 lbs without rescaling the power system. The move you could make today would be to hack cells off your battery setup. Less cells mean less amps drawn, and you can also scale back on cell capacity. SO, with the same fans and motors you could probably lose 2 lbs off the battery pack and still have plenty of thrust to fly a 22 lbs plane. For a complete rescale of the power system, 2 Midi fans & motors at about 1 lb each plus 8c 3600 for each motor (1.5 lbs each) would be 5 lbs of power , making maybe 12 lbs of thrust on a 19 lbs airplane. Not ballistic, but a very scale setup. It is a plane made to fly on the wing, and I doubt it would dog around the sky with lower power. There are other 90-100mm fans that will weight about the same but put out more thrust - at increased cost though. That said, 14 lbs seems a bit high on a 2m plane for structure. Look at the landing gear. I wouldn't take lighter retracts and struts unless they are well overbuilt. But replacing metal hub jet wheels with plastic hub scale robart wheels and dropping the brakes would save some weight. But I'd wait until the overall airplane weight drops to 20 lbs or below to do this. Things go hand-in-hand. Then look at your radio (avionics). How much of your weight is in the RC system? Super-manly digitals on all surfaces would not be called for on a plane this size. An extra oz of weight on 8 servos would be a half pound. I don't know your setup thoough. GO ahead and open that new thread. We'll all be happy to sit here like crows on a fence line. Do it this way, do it that way, skwawk!
Posted on: 2/7/2009 8:48 AM by Author "Johng" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=8448329