stunthanger.com
Speed,Combat,Scale,Racing => Scale Models => Topic started by: Joshua Harel on December 09, 2012, 10:53:06 AM
-
I have been enamored with Homer Hudson's P-51 for many many years and got his plans enlarged to 60". I have a Saito 62 that I may use for it. I want to build the model as a high quality scale, but - not for competition work. I will probably not even employ throttle control - the goal is to keep it light, accurate and fun. Mild aerobatics at best.
What do you scale guys in the know think? I appreciate any and all thoughts, comments and, suggestions.
Joshua
-
Sounds to me like a really fun project. I would suggest you make provisions to ad throttle later just in case you want to have even more fun with it. Touch and go's are lots of fun. Three line is simple to do and enjoyable.
-
Hi Will
I like your suggestion, will certainly add that feature. I am thinking that coupling the throttle to the flaps will be a fun way to to perform touch and goes.
Thanks
Joshua
-
I don't believe I'd couple the throttle and flaps. When you drop the flaps, sometimes you need to feed in some throttle to stay ahead of the power curve and if they're coupled together, I think you might start a mad cycle of need for power and flaps? less power! less flaps! more power! less flaps! .....weeeell, I think you get the idea.
I seriously think they need to be separate operations.
-
I thought about what you say. I do not have a J. Roberts Bellcrank yet so am not familiar with exactly how it works, however - on the plans, Homer Hudson shows flaps and radiator coolant doors operational and I doubt he had an electronic gizmo back in 1965 so I assume that somehow he operated every feature mechnically through the bellcrank and 3 lines. That does not mean of course that he coupled the flaps to the throttle. Just a though though and I will appreciate your counter back: If at full throttle the flaps are level with the wing, at full power or slightly less the flaps are not deplyed. However, beyond a certain point, if you further reduce speed, the flaps will linearly go down until fully deployed at idle - why is this wrong?
-
I suggest you go read the rules for scale at the AMA site. Most options like flaps, bomb bay doors, lights and retracts had to be separate from the throttle or even the elevation lines.
-
John
I am not going to build this Mustang for competition. A simple, reasonable logic will do.
Joshua
-
Just do it! Would love to see pic's of the final product.
-
I'm not saying the coupled flaps would "wrong", it's just that with the throttle at idle with the added drag of full flaps, you can get so far behind the power curve that you might drop like a rock. Power controls decent, attitude regulates speed on an approach.
You can try it, then if it gives you lots of problems you can always uncouple them. That's the beauty of this hobby/sport, we are free to experiment and if it doesn't work, we have license to change something and try it again.
Go with your instincts! I don't think anyone here will say you're wrong to do so. At least I won't! There isn't room here for me to list all my failed experiments! (Don't ask me about running power up insulated lines to operate a modified throttle servo back in the 1960's!) ~^
Please keep us posted on progress with pictures. This sounds like really neat project.
-
Many a NATS winner has flown with flaps connected to, or controlled from, the throttle of a 3-line system. I personally used such a method, first in a Zlin Akrobat (my first one; the second one had digital controls down the lines - in 1975!), and a Fairchild PT-19 (1st place NATS winner in Sport Scale). But there were countless others before me who controlled their flaps with the throttle.
I wrote about my method in the May 1980 issue of Model Aviation. Basically the flaps would come up at complete full throttle; and they would come down at approximately 1/3 throttle. It worked with an old "Digipace" dc servo and 2 micro-switches positioned on the throttle pushrod (the article shows a drawing).
When sitting on the runway at idle ready for takeoff the flaps were down. Advance the throttle to almost full throttle to takeoff with the flaps down. At cruise altitude a momentary blip of full throttle would trigger the servo to lift the flaps. Then throttle back to cruise speed with the flaps up. The flaps would stay up until the engine was throttled back to a speed that I thought would simulate the downwind leg of a full-scale landing pattern, approx. 1/3 throttle. At that point the flaps came full down and stayed there as long as I didn't go back to full throttle. I could adjust the throttle setting during landing without affecting the position of the flaps.
It all worked quite well actually, although a proportional digital system is of course way better.
Mike
-
page 2
-
page 3
-
Hi Joshua,
I have looked at the article and plans every since it was published. What threw me was Homer saying he had to put three POUNDS of lead in the nose! Wow, just how heavy was his model?
However, I am sure it could have been built much lighter and it will be easier to build lighter in the enlarged size. Homer used a K&B .45 Green Head on the original, probably a little bit underpowered.
Best wishes on the build! (and think light!)
Bill
-
Mike
Thank you so much for your posting. I truly appreciate your input. I am not planning to compete, just want to have fun and be able to do Touch and Gos. I don't plan any other functions beyond throttle and flaps.
Bill
The way Homer built his original Sharp Shooter he used 3/8 sheets for the sides plus a lot of blocks. He also had the radiator scoops operational and the tail group was made from 1/2 thick sheets. I do not know what was his reasoning but it flew well enough at 8-1/2 lbs to capture 3rd place. On a 46-1/2 inches wingspan, I would think that one would have to be extremely careful if keeping the weight down is a priority. I assume that scale models do not have the severe weight restrictions necessary for stunt. If you basically fly straight and level plus touch and go, well - the wing loading could go much higher. I plan on Very Much lighter model.
Joshua
-
There's a club member who did that to a model and it seems to work very fine, regardless of anything else.
If it's about some fun, I'd say go for it!
Check here:
http://stunthanger.com/smf/index.php?topic=27114.0
Marcus
-
Marcus
Thanks for sharing and kudos to your friend, very, very nice model. Looks like coupling the flaps and throttle works great.:)
Joshua
-
Marcus
Thanks for sharing and kudos to your friend, very, very nice model. Looks like coupling the flaps and throttle works great.:)
Joshua
I'm happy you liked.
Don't forget to share your results... Gee, I love Mustangs!!
Marcus
-
I'm not saying the coupled flaps would "wrong", it's just that with the throttle at idle with the added drag of full flaps, you can get so far behind the power curve that you might drop like a rock. Power controls decent, attitude regulates speed on an approach.
Unless you're making an instrument approach...
-
Unless you're making an instrument approach...
I used and taught the same procedures on instrument approaches. I know some don't buy into it, but when I took my CFII check ride a hundred years ago, (seems like) the examiner and I talked it over and it turned out he endorsed the same techniques. Granted, the varying situations one can get into in the three dimensional world up there can force some altering of any procedure, but, for me, the basic was as stated.
-
One reason heavy scale models do OK is the ability to land, dead stop, and do the taxi lap without having the engine throttle down close to quitting.
Lighter models that do proper high flight and maybe even a loop or wingover often have trouble throttling down low enough to land and do the taxi lap without accidentally taking off.
Flaps sort of work against good touch-and-goes and taxi laps. They force you to slow down even more to get the model to land and stay down.
-
You might consider a P-51 ARF in the same size range and give a try, the nice thing about ARF's is that you can experiment with new ideas and actually try everything before building the real deal. When I fly my RV-4 with flaps I drop the throttle to maybe 1/2 power and then deploy full flaps with the electronic controls (separate from the throttle) and then land. The flaps don't come down too far so the model does not slow down that much. After landing then I raise the flaps, or sometimes take off with the flaps down.
On a different model that had much larger flaps and came down quite a ways when you lowered the flaps the model nose pitched up and I had to feed in down elevator to keep the model level. When the flaps were raised the nose droped and had to feed in up elevator to keep the model level.
Flaps are a lot of fun.
Fred Cronenwett
-
Interesting. How would you control your descent rate in sailplane?
Not being a smarty pants. The premise of the conversation is about tying flaps and power together.
Flaps control the approach angle... That's what they do. They change the aircraft's configuration. They are also draggy, so yep, you need to add power to maintain the same descent rate.
-
In a sailplane you get down in a hurry with spoilers on top the wing, like anti-flaps. Making drag while killing lift. In some ways, light model airplanes are like real sailplanes, too efficient to come down.
-
Like yourself, Chuck, I'm not trying to be a smarty pants, but I would never make an instrument approach in a sailplane. :) I always wanted go up in one, never got to because I allowed me to be way too busy. I feel I missed a great opportunity by not going.
Yeah, I know it's not too late, but, well, still busy ya know.
You're spot on about the flaps and the rate/angle of descent and power, and truthfully, this discussion has been going on for as long as I can remember being a pilot. There are two camps, and the interesting thing is, at least in my opinion, neither camp is wrong because both approaches, (ooo, baaaad pun!) work. The examiner I mentioned chuckled and finally closed out his comments with, "Whatever works."
-
John
I am not going to build this Mustang for competition. A simple, reasonable logic will do.
Joshua
If you are not going to compete Joshua, the simplest setup would be to use an inexpensive 2.4 gHz radio system. The ability to use standard lines, or even Spectra, no third line, along with easy adjustment of the throttle throw makes it pretty easy to use.
-
Thanks to all who offered advice and opinions. Since my intial posting I received much valuable input and guidance from Clancy Arnold and based on what I have learned, I revised my plans. As it stands right now I am finishing a special handle with 4 control functions: Throttle, Flaps, Retracts, and, Rudder/Tail Wheel steering. I am painting the handle right now and by this weekend hope to complete the UTronics installation. Due to availability of fiberglass components, scale spinner, and canopy - I have ordered the plans and parts for Brian Taylor's 69" P-51D. They are without a doubt the most accurate scale plans for a P-51D ever. I have a Saito 82a engine and will most likely start building next month. I expect it to be quiet long term project, probably around 2 years to completion.
Joshua
-
Wow, Joshua, that sounds so very neat! I can't wait for pictures of the build as you go along. I think you'll love the utronics setup!
-
Thanks Will.
The attached picture of Brian Taylor's prototype will give a good idea of the scale fidelity potential of this P-51D.
-
To test one of my favorite paint schemes, I built this 27" wingspan paper model of "Hubert" during Xmas to get a 3-D visual impression.
-
You have quite an undertaking there. I remember a couple of scale modellers out in western KANSAS that said scale models are never complete. Jeff Perez was one of them and Bob Simmons was the other one.
-
I agree but let's face it, if scale was easy - everyone would have done it.
-
Update:
Before starting to cut parts, I wanted to have all the necessary hardware in hand. Obviously - the engine is a critical part. I did a lot of research and it is obvious that for the most part a 90 size four stroke is about as large as most would go. I envision the finished model will probably weigh in the range of 8-10 lbs, so, I had to decide between a Saito 90 and the new OS FS-95V. I hate noise so this is also a prime factor for me. I read whatever I could find on the new OS FS-95V (not a whole lot out there), and what got my attention was the fact that the engine is a real torquer and has a muffler designed for low noise. I decided to invest in one, and broke it in yesterday and this morning. I tend to run my engines slightly rich so, I broke it in with a Master Airscrew 14-6 on Omega 5% Nitro Castor/Synthetic mix. Here is what I found out:
At full throttle with the 14-6 the engine can turn in excess of 10,000 rpm.
Idle can get down reliably to around 2200 rpm.
Vibration level is extremely low.
Deep growling sound - even at wide open sound. None of the obnoxious shrill of 2 strokers or even high performance screaming 4 strokers.
I than switched to a Master Airscrew 15-8 which is the largest recommended by OS for Scale Models using this engine - 7500 rpm wide open.
I have seen a test on youtube where this engine spun a 14-6 prop at around 11,000 rpm and produced 9 lbs of static thrust.
To sum up my experience so far: Absolutely Fabulous little gem! The easiest to tune engine I ever ran, noise friendly, extremely powerful and steady runner.
In addition to the engine I just finished building a handle with 4 control functions.
Time to start cutting wood:)
-
Nice job on the handle!!!! #^ #^ y1 y1
-
Thanks Will :)
-
Oh my....I can't waite to watch this one go together. The only thing that would make this perfect is if the plane was a Spitfire! I'm Canadian so I got to say that! H^^ I wished I had some skill as a builder cause I would like to do a scaler. I have a Sig clipped wing Cub that I have been saving.
-
Glenn
I would encourage you to look into a Brian Taylor Spitfire. Start by finding a build thread for one here: http://www.rcscalebuilder.com/forum/forum_topics.asp?FID=4, this will give you a very good idea what it takes to build one. Parts and plans are available here: http://www.bhplans.com/BTPlansPg1.html and here: http://www.trapletshop.com/gb/c/1168/modelling_plans_and_parts
Joshua
-
Really cool handle!! Makes me feel like building a scaler too!!
Marcus
-
Joshua:
That is a really great job on that handle! What is the black device on the extreme left of the handle assembly? Also, what is the yellow material that you have finished the control panel with? Is that just paint?
Jim Fruit
-
Joshua:
That is a really great job on that handle! What is the black device on the extreme left of the handle assembly? Also, what is the yellow material that you have finished the control panel with? Is that just paint?
Jim Fruit
Jim
The black device is a Trim Pot from an RC Transmiter. It is for fine tuning the idle and shutting the engine down. The yellow back ground is a simple Krylon spray can from Walmart surrounded by permanent marker's black line. Attached is a close up picture.
-
Throttle idle trim pot.
-
Joshua,
Wow! Nice!
You did a great job with the handle also, peppered with some paint? Looks great!
Charles
-
I want to know if this beautiful piece of equipment will be for sale some day? #^
Blessings
Allen
-
Allen
Perhaps, but not before I try it on the P-51 :)
Best Regards
Joshua
-
In reference to reply #20 by Fred Cronenwett:
Fred wisely suggested getting an ARF and converting it to CL to serve as a test bed, back-up and a trainer. Well, the opportunity presented itself today on RCGroups in the form of a Top Flite Gold Edition P-51 "Big Beautiful Doll", 65" wingspan airframe. The asking price was less than half that of the kit, and, this is a complete airframe that has been flown as RC before and the builder moved on to other planes and gave it to a friend who is into foammies and is not interested in putting the P-51 back in the air. I will head to Atlanta, GA Friday to pick it up. I plan to convert it to CL rather quickly since I already have the engine, retracts and servos. I anticipate that it will be very close in performance to my intended scratch built P-51D model while serving as good practice and intro to CL Scale. Pictures can be found here.
http://www.rcgroups.com/forums/showthread.php?t=1813802
What do you guys think?
Joshua
-
You will have fun doing that, it will work on the bench and then when you actually get to the flying field you will learn a bunch more. I made a bunch of mistakes on my first couple planes and learn from every one of them. Once you start flying with electronic controls you learn very quickly what to do and what not to do.
Nice thing about the P-51 is the wide track gear, very stable.
An adjustable leadout guide will keep the line tension reasonable.....Haven't had a P-51 in awhile, but fly the spitfire and corsair all the time.
Fred C.
-
Fred
Thanks for the input and encouragement. I have a PDF copy of your book on CL Scale. Shall I follow the recommendations for bell crank installation per the book? Does the bell crank go on the horizontal center line of the plane (engine thrust line)? Any other practical advice you can offer is most welcome.
Joshua
-
I put the bellcrank towards the outboard side of the fuselage so when it swung thru it full range the lead outs or bellcarnk itselftwould not bind against the sides of the fuselage. The location of the bellcrank is not really important since the CG and the location of the leadout guide at the wingtip determine how it will fly. Most of my models have the bellcrank bolt 1/2 to 1" behind the CG.
On the P-51 you will want the bellcrank just above the wing in the fuselage, don't put it too high becase the vertical location also matters.
Hang the model from a ceiling and put the leadout guide so that the nose is flat to the floor (bare minimum) or slightly down. The more outward the fuselage points the more line tension you will have. I always start with too much line tension and then move the line guide forward until the line tension is enough to maintain line tension.
Fred C.
-
"On the P-51 you will want the bellcrank just above the wing in the fuselage, don't put it too high becase the vertical location also matters."
Questions:
When you say "Just above the wing in the fuselage" do you mean just above the wing cradle in the fuselage? (since this is a removable wing).
Also, the fuselage is probably about 4" wide, why would there not be enough room for the bellcrank to swivell around even if mounted on the center line? I plan on using a 3-1/2" - 4" bellcrank.
Thanks
Joshua
-
(Clip)
The location of the bellcrank is not really important since the CG and the location of the leadout guide at the wingtip determine how it will fly.
(Clip)
On the P-51 you will want the bellcrank just above the wing in the fuselage, don't put it too high becase the vertical location also matters.
(Clip)
Fred C.
Hi Fred,
Your first statement is absolutely correct. The longitudinal position of the bellcrank can be anywhere. The leadout position, relative to the CG is what is important. (Yes, you still want to position the bellcrank where it makes sense to do so structurally, and where there is room, and it is desirable to have minimum angular change of the leadouts at the guide exits.
Just as it makes no difference longitudinally where the bellcrank position is, its vertical position in the model can be anywhere. Again, it is the leadout position relative to the CG (longitundinally AND vertically) is what is important.
With a low wing aircraft and its dihedral (the P-51, for example), the bellcrank can be in the wing, the leadouts come out the tip and because of the dihedral, the leadout position is desirablly fairly close to the vertical CG of the model. Experience has shown that it is desirable to use flexible cables for the leadouts rather than solid wire. The flexing of the leadouts and the wear on the leadout guides are not issues.
Keith
-
Keith
Thanks for your contribution. Does this mean that I can literally place the bellcrank in the wing? I don't recall ever seeing a picture of a low wing WWII plane where the leadouts did not come out the side of the fuselage. I hate those and would much rather have the bellcrank in the wing where the only portrusions are the ends of the leadouts coming out at the wing tip.
Please elaborate some more.
Joshua
-
That is going to give quite a pull!!
I love mustangs H^^
Marcus
-
Joshua,
One thing that complicates putting the bellcrank in the wing when the wing is removable is that you have to make provisions for attaching the pushrod. This can be a real hassle. I did this with my HS-129, but prefer the bellcrank in the fuselage of all my other models with removable wing.
Also make sue your bellcrank mount can handle the "g" forces from flight. With a competition model it has to handle the dreaded pull test too.
Chuk
-
Chuck
So, what you are saying is that apart from the dreaded pull test, the only reason for installing the bellcrank in the fuselage is to avoid connecting and disconnecting the elevator push rod every time the wing is mounted to the fuselage or removed?
Joshua
-
There are a lot of misunderstandings about bellcrank position. What is important in a control line model is where the leadout guides are relative to the CG. Remember that the CG is a single position located located longitudinally and vertically. So it is important that the leadout guides be properly positioned relative to that CG both longitudinally and vertically. This means the leadout guides on the inboard wing will be several degrees aft of a line perpendicular from the CG (top view of model) to locate the longitudinal position of the leadouts. The size of that angle is determined by the position of the leadouts relative to the CG and is dependent on model weight, speed, and the length and diameter of the control lines. Those leadout guides should also be at or near the same level as the vertical CG of the model.
It is desirable to locate the bellcrank longitudinally relative to the leadout guides so the leadout cables are raked rearward to allow for the aerodynamic drag of the control lines to minimize the wear of the guides and flex of the cables and attendant drag of the cables through the guides. (This wear on the guides as well as the drag, or friction, of the cables through those guides is almost of no consequence if there is reasonable alignment of the leadout rake to the control line connections.).
On a dihedraled wing like on your P-51, having the bellcrank in the wing and the leadouts coming out at the tip means that indeed, the leadouts guides are above the bellcrank position, but those leadout guides are somewhere near (and close enough to) the vertical CG position of the model. Yes, there will be some flexing required of the leadout as they pass through the guides, but that flexing is of little consequence. The drag is almost inconsequential and the wear on the guides is of no significance unless you are talking about thousands of flights.
I know, in the earlier years of CL flying, many scale models showed the bellcrank in the fuselage with the leadouts positioned above the wings through a guide above the wing tip. (Many of Walt Musciano's 3/4" scale designs showed this.) Please be aware that there have been any number of very successfull CL scale models with low wings and dihedral with the bellcrank in the wing and the leadouts through the tip. This would include the plans for your Homer Hudson's P-51 Sharp Shooter ( Model airplane News, Jun, 68); Jimmie McCroskey's Senior Scale Nats winning P-51 (MAN, May, 55); Malvin Meador's Open Scale Nats winning Spitfire (AAM, Dec 72), and any number of successfull published designs. (I could list a dozen more, but think you should get the point.)
Yes, it is important to have the leadout guides properly positioned relative to the CG. This is a critical function in the trimming of a CL stunt ship where precision and smoothness in the maneuvers and varying wind conditions while flying through those maneuvers is important. In a CL scale model, that level of precise leadout position is not nearly as critical. It is interesting to note that in the pioneering super semiscale stunt designs by Al Rabe, he placed the bellcrank in the wing, the wings have no small amount of dihedral with the leadouts coming out at the tips probably very near the vertical CG of the model. Those systems work and work very well.
Hope this makes sense.
Keith
-
Joshua, I'm reacting to the CG location factors that Trostle is talking about. I have tried to have the leadout guide on my scale models in line with the vertical location of the CG. On most of them that means the bellcrank was in the fuselage and the guide on top of the wing. I prefer to avoid the loads imposed on the guide when the bellcrank is out of line, even if they are small. Connecting the pushrod while assembling my HS-129 would not be a problem if my hands were 1/4 their current size and if I had three extra joints in my fingers. ;D
Speaking of the bellcrank mount, let me suggest you support the bolt above and below the bellcrank. The pull of an 8 or 10# model puts a lot of overhung load on a bellcrank mounted on a single platform.
Chuck
-
Keith and Chuck
Thank you both so very much for the superb guidance. I read what you both said and fully understand the important relationship between the the guide wires rake angle and the CG location. There is one question though I still have:
I have been a modeler for almost 50 years now and have built, balanced and flown many models. In all these years I cannot remember ONE instance where I balanced a model along the yaw axis (vertically), nor have I ever heard of anyone doing so. At best it would be quite difficult to do and it seems that it is not critical at all. Do you gentlemen actually balance your scale models vertically?
Joshua
-
Joshua
You might want to check CLW jan '13, pgs 64-67.
It's a good start.
Marcus
-
Marcus
Thanks for the heads-up but not being a PAMPA member I do not have access to CLW.
Joshua
-
Joshua, I'm reacting to the CG location factors that Trostle is talking about. I have tried to have the leadout guide on my scale models in line with the vertical location of the CG. On most of them that means the bellcrank was in the fuselage and the guide on top of the wing. I prefer to avoid the loads imposed on the guide when the bellcrank is out of line, even if they are small.
Chuck
Chuck,
I am not trying to argue here, but I will explain what I have experienced over the years. Yes, it is desirable to have the bellcrank line up with the leadouts and lines to minimize the amount of leadout flexing that would otherwise occur at the leadout guides. However, that flexing and the loads imposed by the leadouts on those leadout guides is really not that significant. I will explain two different real scenarios to illustrate this.
1. Some time ago, Walter Williamson wrote an article in American Modeler, Jul 66, titled "Case of the Wandering Bellcrank". In this article, Williamson built a 35 size sport/trainer type model where he could locate the bellcrank in nine positions, from six inches in front of the CG to 10 inches in back of the CG. The plane flew the same regardless of the bellcrank position.
2. I mentioned the Rabe semiscale stunt models that all have dihedral. All of his airplanes have the bellcrank in the wing with the leadouts at the wing tip. Needless to say, his airplanes perform superbly. I built the F8F Bearcat from the Rabe plans a "few" years ago with the dihedral shown on the plans. This has the bellcrank in the wing, essentially near the bottom of the fuselage. And that is a "rather deep" fuselage. The leadouts come out the wingtip, probably slightly below the vertical CG. That airplane has well over 1,000 flights on it over the past 12 years and there is virtually no wear on the 1/8" ID brass eyelets used for the leadout guides. (The leadouts are cables, not solid wires.)
To me, this all represents that the loads at the leadouts are essentially inconsequential when the bellcrank is not exactly lined up with the lines/leadouts/line rake while the model is in flight. And this is experience with CL stunt models where the leadout position is a critical item in the trim of those airplanes. With CL scale, the bellcrank/leadout positions are even less critical as long as the leadout guides are a few degrees aft of the longitudinal CG.
That leadout guide position can be calculated by one of the several programs that have been referenced on these forums. But for CL scale, Bill Netzeband presented a table that gave examples of appropriate leadout line rake for a wide range of models that would encompass most CL Scale projects. Lo and behold, those successful scale models I referenced in my previous post and others I have in my file have the leadouts generally in the location that the Netzeband tables suggest. It really boils down to just have the center of the two leadout guides positioned 2o or 3o behind the longitudinal CG position, (maybe slightly more, like 4o) if heavy lines are used or if the model is really light. The vertical position of the leadout guides should be somewhere in the area of the model's vertical CG. Then position the bellcrank where it makes the most sense to do so based on available space and needed structure to hold the thing.
It is interesting to me that the Homer Hudson plans show the bellcrank in the wing and where the leadouts go. I do not think there should even be a question about what to do with that airplane.
(By the way, I have your profile Hornet in that file I mentioned. Bellcrank is in the wing also and yes, the leadouts come out of the bottom of the wing outboard the engine nacelles closer to the tip. I have stated before that your Hornet sets the standard for what a CL Profile Scale model should look like. It well deserved the special recognition it received at the 2000 Nats.)
Keith
-
Marcus
Thanks for the heads-up but not being a PAMPA member I do not have access to CLW.
Joshua
Hi Joshua,
CLW=Control Line World, a Brodak product and not connected to PAMPA.
BIG Bear
RNMM/AMM
-
Thanks Bill. I am not subscribed to it either.
-
Joshua
You could try contacting Clancy Arnold, he wrote the article.
Marcus
-
Joshua, no I don't balance my models vertically. I make a guess based on side view distribution of area (like nacelles below the wing), location of engine and expected mass of landing gear.
Keith, We're not arguing; we're focused on different aspects. I am more of an engineer and believer in Newton's laws than I am a serious C/L aerodynamics person, and I have always "known" that the bellcrank could be anywhere. My models were all built for competition and as such I tried to reduce any factor that could negatively affect scoring. My Typhoon and HS-129 both weigh 15# and line tension is probably over 30# (more if I open the throttle wide). This is very different from any stunt or sport model I've flown, but reminiscent of my class 2 carrier Dark Shark from the Consolidated kit. I figure the CG is going to try very hard to be directly outboard the leadout guide. That sets up the potential for the model to be rolled from wings level flight. This rolling moment is what I've tried to avoid.
Thanks for the compliments on the Hornet. It worked so well that I never had a desire to build a replacement. I still fly it on the rare occasions when I enter a contest and it is still competitive. Being a profile model, the wing is a rational place to put the bellcrank. And with the engines and bulk of nacelles are below the wing, the vertical CG is undoubtedly below the wing too. Originally it may have had the pushrod hidden in the fuselage (or maybe that was an XF-5-F that preceeded it). I had to rebuild from a crash and put the pushrod external where it could be attached easily.
Chuck