sjhanc

My Feedback: (3)

rossmick,
Was the spar you removed defective in any way?

rossmick

Sjhanc
No the lower spar was fine. It was just much easier to remove it than to try and cut all the area in between the spars and make the new spar fit tightly in between. The way the spar was glued in it would have been of little use in a high stress condition. Not sure what they call glue, but it is really not doing a great job of binding surfaces that transfer load. I use Titebond, and the material will give way before the glue joint. I know I am off on my own here, but this new spar really seems the answer to many of the issues with this wing. Because I am going to spend all this time upgrading the design I might as well do the best I can. More to come, the gussets for the gear mount angle will be another alum angle bolted to the spar with a blind nut and then bolted through the gear mount angle and the rib. This should help transfer the twisting vector in to the solid spar. I may put some heavy gussets on the ribs behind the spar gear area to help transfer load to those ribs as well. I might even double or ply those ribs, but hate cutting the skin up any further (second thought, maybe all new skin correctly glued would be a vast improvement all in its own. Bet the top shin would let go first, but I will CA every joint I can get to). Any way, I am enjoying the project and it can't hurt.
I hope you had a good weekend to fly, we actually got rained out for the last three days - first rain in about four months.

rossmick

Spent today designing and cutting the alum gear hold down ribs. This time I made sure there was no binding from one bolt down surface to the other. It does not take much to stall even the pneumatic gear or at least make it travel slower. Don't ask me how I know. Company coming over so had to knock it off after four hours. Now all items are dry installed and it looks pretty decent.
Tomorrow I will install bolt locations, add extra rib thickness behind the spar at the gear rib locations and glue up. I will have to cut the webbing to make sure the added ply ribs contact the solid spar and not the webbing. I'll add gussets to insure a solid and strong connection to absorb the shock of the gear twisting back. I hope to be able to reskin on Tuesday, but plan to fly in the morning so will only have half a day.

sjhanc

My Feedback: (3)

rossmick,
it looks like you are making good progress with the repairs. I took the day off from working on models and the car to go flying. We had 30% cloud cover, enough to keep the temp down in the high 70s and random wind from 3-5 mph. Everyone got good flights, no dorks or crashes and lots of warbirds in attendance. As the afternoon wore on the wind dropped and the sky turned severe clear blue. I had one of my better days, everything worked and I greased my landings. Today was my last opportunity to fly my Mustang for a little while, I have to put it aside and get my electrics ready for a club event next weekend. All of my jet's batteries are five years old and have begun puffing and going dead. I ordered 3 new batteries but they sent them with the wrong plugs, I use deans, so I have to change the plugs.

My razorback P47 is ready to fly after I charge its flight packs. It seems strange to not have a plane needing repair, and only one under construction. This will probably change after next weekend. On your wing, I used to pour Zap in all the servo and gear access holes on everything I could reach, then drill tiny holes to get glue into sealed areas. After my first TF wing turned out to have no glue in the right panel, I have never trusted ANY ARF brand to do right by us.
Stay busy,
Steve

rossmick

Got a late start this morning, but got most of the plan completed. I cut the alum angles for the gussets but decided to just use wood. Rear gear ribs were expanded with ply ribs glued on both sides and then glued them with gussets to the main spar. Pulled the wing together with plenty of glue on the spar and attach points. Decided to tap the alum gear hold downs to bolt them to the front ribs. Idea here is that if they should get damaged they could be removed and new installed. Then started to tap the gear mount holes for the gear. Ran out of energy and time so will finish taping in the remaining holes for the gear mounts tomorrow. Will install air lines, wires, and flap and aileron hinges before reskinning I believe I will try the split flap concept, but need to figure out the configuration for the hinges.

Is anyone else having problems uploading multiple photos from the attachment selection list? I get one photo to upload fine but an error message when I try more than one.

sjhanc

My Feedback: (3)

I posted photos of the dummy wing and flap simulator to work out the positions of the hinge pin locations. I'll dig them out of my picture file and post it for you. As installed, the flap is almost touching the wing's trailing edge at the top, closer than the first picture. I got the wing trailing edge shape by gluing triangle stock at the top and bottom, then sanding the curves in with sandpaper glued to a dowel. The ARF wing structure is thin in this area so after I got the shape I wanted, I glass the edge with 2 oz. cloth and epoxy, with lots of micro ballons to keep the epoxy weight down and make finish sanding easy. The fourth picture is the back side, turned around to show how a pin hinge is secured in an adjustable way. Notice the low metal pin location. and where it is, way back in the flap. Robart hing sockets are necessary in the wing to prevent hinge flexing. I also built a drill guide to get the holes and their angles in a straight line. The critical spec. is the location of the metal hinge pin, this must be constant along the flap span. The hinge holes can be what ever works for you. The stock flaps can be uncovered at the leading edge and a strip of 3/32 balsa added to the front so that there is enough wood to sand with out getting the leading edge too thin. The slot curves are not my design, I copied them from slotted wing flap structure pictures I found on the internet. I wanted a simple to apply solution and this works better than I thought it would. I did stall testing at high altitude, and when deployed the slots give a more solid and stable slow approach. Since it worked well for takeoff and especially landings I did not try to find the limits of the envelope.

The characteristic I like most is when used at high flap deploy angles, (I use 55 degrees full flap) a high engine idle is necessary to keep a constant slow approach speed, you don't want it to decellerate during the final approach. The ailerons are less effective, so turn it with rudder, keeping the bank angle shallow and on final, put the nose down for a steeper approach (necessary at my field to clear the west treeline of 40 foot trees 250 feet from the runway). I always fly a military break using a turn just large enough to be over the tree line and at a constant descent rate. The plane is 20 feet above the trees on base, and as it decends and turns on final it is already clear of the trees. Guys who fly a straight flat approach often hit the trees, depth perception is difficult at best. On final, nose down acceleration is minimal, and the excess speed scrubs off as you level for touchdown. All of the 3 TF models I used this on were flying at 28-33 lbs, gross weight, and if the H9 plane had shown landing stall tendencies like the TF, I would have slotted its flaps also. At touchdown I only reduce power by a click, letting the plane's weight slow it while the prop blast maintains air flow over the tail for best control. We have a long smooth runway, so I let it roll as long as it wants to. Before I modified my tailwheel struts to eliminate the ground loops, I used the grass next to the runway for operations, the plane behaves better off of grass, as all taildraggers do. Now that my TF planes are retired, all of the high stress landings are just a memory. The H9 Mustang is so easy to land that I don't do more than 1-2 t&g landings for practice. Saturday I managed to grease 3 landings with no practices, and only did 1 go-round for a long landing that was possible, but might have run it out into the rough and damaged the gear. Incidently it takes me 3-4 hours to modify the flaps on a new wing. I did it on a completed wing and extra time was needed to remove the hinge pockets in the wing and the pin hinges in the flap. Then it was necessary to fill the holes with balsa plugs.

The field experts, none of whom have ever owned or flown a P51 will tell you to raise the flaps at touchdown, that is just extra workload at your time of highest mental workload, and isn't necessary. I stopped the practice of not using flaps for gusty crosswind conditions, as long as you are ready to add power quickly if the wind stops, the P51, next to a Cub, is the best crosswind handling plane you can fly. I practised landings in 18 gusting 25mph with the wind 30 degrees off the runway center. It was WORK, but not difficult.

sjhanc

My Feedback: (3)

You mentioned the upload problem with multiple pictures. I get around that by selecting each picture and uploading before selecting the next to up load. If you select several to upload all at once, the data packet exceeds the 1 megabyte limit for uploads. The text and the pictures together are just too large a file unless you edit the pictures and reduce their dot count to low resolution. All of the pictures above are between 400k to 500k file size, so one picture plus text is all you can get to upload at one time. The up load popup will let you select and upload single 1 meg or less pictures all day. When I took these pictures I set the hinge thing on carpet, adding carpet detail to the file size, it is better to place your subject on a monochrome surface. The single color is compressed to a minimal file size because each individual dot is the same as all the others. Only the object requires additional uncompressed data bits.

rossmick

sjhanc
As I save the pages in a thread that I want to refer back to by make a favorite entry with a descriptive title so that I can go back and look it up. So I had a good reference to your flap idea. However, I want to thank you very much for making the effort to help by resending the photos. I am thinking the leading edge of the flap is symmetrical as it should match the curve you sanded in the trailing edge of the wing.
I had one of those days when you take three steps forward and two steps back, broken taps, dull drill bits, mismatched holes and a trip to the hardware store. Only thing I can say is that I did not give up until I had all the gear installed. I am pleased on how the wing and gear upgrade has gone, but it sure is a lot of work and a lot of parts. Time will tell if it is worth all the effort. Hopefully, I will close the wing tomorrow and get on to the flaps and ailerons.

sjhanc

My Feedback: (3)

On the flap curves, I didn't want to re-invent the slots so after building my simulator and seeing how the 2 curves work together to facilitate high speed air flow through the slot, I just copied what I saw. I actually printed the drawings and traced their outlines on the wood at each end of the flap, then sanded to the outlines. The aerodynamic theory is that, the deflected flap creates high pressure in the bottom hinge area, the curved entrance encourages this air pressure to escape into the slot, where it is accelerated to a speed higher than air coming over the top. The top flap curve keeps the high speed flow attached down the top flap surface, and the high speed jet encourages the air over the top of the wing to follow it downward, increasing lift more than a simple closed hinge flap which does increase lift, but also a lot of drag turbulence following the flap.

This extra turbulence reduces smooth air flow over the tail surfaces and makes the slow speed control less effective with a higher stall speed for the horizontal stab (also known as, 'running out of elevator control during the flare'). I don't 'flare' my planes at touch down, I'd rather just hold a positive angle of attack and fly to the runway with throttle. The TF P51 does not always react in a predictable manner at the 'flare'. It will drop the left wing and cartwheel. At a lower gross weight than 22 lbs. a 'flared' 3 point landing can be done easily with proper throttle management, but timing and speed control is everything, not easy when you are not IN the plane.

My H9 Mustang can be set up in a 3 point attitude on the downwind and flown all the way to touchdown easily, but spectators want to see it landing 'on the mains', that is what gets applause for a well done landing IF it doesn't bounce.

I am getting my electric models tuned up for this weekend's electric only event. Today I test flew my F16 jet in my yard after a hanger rash repair to a crushed r/h flying stab surface, it only needed a little roll trim for level flight. With that plane done I am working on my big P47 razorback which only needs battery cycling and charging. It only has 4-5 flights since new, but I haven't had to do any work on it so it won't need testing before the event. My only flying difficulty with the P47 is its tendence to 'float' down the runway, staying in the air well below its stall speed, probably due to ground effects.

Your wing mods look pretty good, you should have it back in the air soon. One of the guys in my club flew a 1/3 Spitfire sunday, a really nice scaled out model and a smooth flight and landing.

rossmick

Not that is makes any difference, but the flap design is actually a slotted flap. Your explanation is totally correct, but I think awhile back I corrected the use of fowler flap to split flap which was incorrect. Worked today to hunt for a very small air leak. Tested the gear cylinders on their own and they do not leak, but some where in the set up I do have a small leak. It is small, losing 50 lbs. over night, but it still is a leak I can not find with the standard soapy water test. Thinking it might be the pressure gage its self. Gear installed and lines hooked up. Working ailerons and now slotted flaps,.

rossmick

Here is some additional information on slotted flap design.

sjhanc

My Feedback: (3)

rossmick,
The flaps in the second pic look like RC designs, and wouldn't be as effective for creating extra lift. The flaps in the fifth picture have profiles closest to what I used, except for the lower hinge center that would move the flap back, extending the wing chord and increasing wing area slightly. I chose to raise my hinges for an easier install, and to avoid getting too far from a scale appearance. Actual P51 flaps are bottom skin hinged, with the flap leading edge buried in a socket. As the flap deploys, the flap's top surface curve stays close to the wing top skin. It would have been so easy for NAA to do a slotted flap with out increasing complexity or difficulty to manufacture. The half or two thirds scale Thunder Mustang that I saw with slots installed had a Lambo V12 engine for power, an engine also used in racing V hulled boats, usually with 3 engines installed.

The slot design in the sixth pic is similar to the flaps in my TF P47 razorback, except that the P47 designer chose to omit some of the features that increase lift. It does open into a slot, but the slot gets wider at the top than it is at the bottom, actually slowing airflow through the slot instead of creating a jet that accelerates and pulls wing top airfow down the top of the flap. Its huge wing area does give it a very slow stall speed, but I have observed a loss of elevator control feel at landing speeds, most likely the result of flap turbulence destroying smooth air flow over the tail when the flaps are deployed. As a result, the plane lands better with only partial flap deployment. Flaps fully deployed, it floats down the runway in ground effect and is difficult to keep it flying in a straight line, it wants to drift with the wind. It is not much fun to do crosswind landings with either, probably why the P47 guys sit out the gusty crosswind days.

rossmick

I installed the flap hinges very low on the flap and aft of the normal rotational axis. I rounded the front of the flap maintaining the lower angle. It appears that if the lower face of the flap is parallel with the trailing edge of the wing you will get approximately 40 degree of flap. The way the hinges are installed at 40 - 45 degrees you will maintain a constant equal slot dimension from lower edge to top. I also filed back the lower edge of the wing trailing edge to give slightly more angle for the slot. I then plugged the holes in the flap from the original hinge location which will strengthen the hinge in the flap.

Flaps and ailerons installed, and they look really good. It will be interesting to see how the flaps function, as I will find out at very high altitude.

I feel the other really weak area for the gear is the leading edge where the ribs connect. There is really no strength for the downward vector when the gear contacts the ground. What I came up with is a frontal spar of sorts that goes across 4 ribs. This 1/8 ply spar is glued to the skin and gusseted in to the ribs. The outboard ribs are doubled with a 1/8 ply rib to help absorb the load and give the gusset a more solid attach point, I also removed the 1/4 x 1/4 balsa cross beam in front of the gear and replaced it with hardwood 1/4 x 1/4, again, should take more load at touchdown. All items are dry fit and I will glue it all up tomorrow.

sjhanc

My Feedback: (3)

rossmick,
Use drill bits to gauge the slot, make sure it is identical inboard and out board on both flaps. I didn't do this and had a strong roll flaps down that couldn't be trimmed with aileron trim. After I used the drill bits to set the gap the plane went back to normal. Your leading edge reinforcement looks like it may be easier than what I did. I installed a front spar that started at the first rib out side of the gear bay, then went across the front to the same rib on the other wing. It never was tested, I haven't damaged a wing since I did the mods. At least I don't get damage on normal landings like happened with the stock wing. The H9 Mustang lands slower and softer, I have only bent one strut landing deadstick in the rough. The other deadsticks all made the runway. Now I have the engine cooling baffling worked out so no more deadsticks. I got used to the TF plane's not needing baffles in the engine compartment, it was a shock to find another Mustang that had to have them.

rossmick

Thanks for the info on gauging the flaps, so far it looks pretty good. Had time today to do the glue up and install the gussets. Looks like I am finally down to the last of the upgrades, so tomorrow I will reskin. I have had several people at the field comment on how thin and soft the balsa skin was for this size of wing. Everyone was bewildered on why the wing folded and came over to look. Point here, most wing skin balsa is hard balsa and not the soft stuff I see here. Problem is that I don't want to strip the whole wing to get it right. I will use hard to fill in but don't think it will be of much additional value.

sjhanc

My Feedback: (3)

rossmick,
If your installed skin is in good shape and you don't want to re-skin, you can harden the soft balsa by a minimal glass skinning. I use Deft laquer sanding sealer aerosol ( very light, house paint store) on the bare wood to seal it and prevent the later urethane or epoxy coats from soaking the wood and adding a ton of weight (lightly sand between 2 coats). Next I use 3/8 oz per yard glass cloth applied with MInwax water based Polycrylic urethane aerosol furniture clear (Walmart) for the glass adhesive. This is very light and adds considerable strength to the wood. After the paint sets most of the liquid weight is gone. The cloth weave can be filled with epoxy finishing resin mixed with microballons (heaviest, but easy to sand), or light weight spackling from the hardware store (applied with a credit card), then another coat of finishing resin or urethane after a light sanding (lighter). This method is not as dent resistant as a full glass-resin finish, but is a harder skin than soft balsa, film covered, and is much lighter than the full glass resin. Glassing the skin adds more strength than internal reinforcements.

H9 Ultracote silver film can be applied over the glass by following the instructions with the Ultracote, or if you do the whole wing with glass you can use model paints for the finish. H9 or TF silver paint works fine from aerosol but does add weight. A better paint option is Automotive touch up laquer aerosols over automotive undercoat (mostly sanded off) The painted over glass finishes are dent resistant, but will be damaged by rough handling. A film over glass will dent, but can be ironed out, stretching the film over the dent. I use this glass method on my foam jets, it is as light as any other finish you can put on foam and very durable.

I have a large quantity of 3/32 premium balsa on hand to skin a foam wing I bought for an A model P51 that I have canceled. I plan to use this wood to skin my J Bates wing and glass it, but the wing structure is wood frame and it might be better to use a medium grade balsa skin rather than the softer premium grade. An alternative is to use up the premium wood and hard skin it with 3/4 oz per yard glass cloth (definitely heavier). It is a larger plane so the additional weight would add about a pound to the gross. Today I reached the point in the fuselage construction that requires the wing for further progress. I have to switch gears and move to the wing room to restart its construction. It is all framed and reinforced with the retract mounts ready to install, after that skinning is next. I have to decide which methods I will use and get on with it. All of the wing control surfaces are finish sanded and the skinning needs to be done for the hinging to proceed.

In the picture the horizontal stab is wood construction finished with the lightweight glass method I described above, Finish paint is Duplicolor Ultra silver from the auto parts store over automotive black primer. I will spray flat clear over the silver to get rid of the shine.

Early war P51s were painted OD at the factory and camo applied in the field, Later B-C and D models were painted silver as delivered and camo added later by using units or only squadron markings over silver towards the end of the war. All aircraft were filled and primed to eliminate panel lines and rivets for speed, these details re-appeared on aircraft stripped and repainted by users, especially ex military aircraft privately owned after the war. The only panel lines visible were the gun bay panels and wing tip panels on combat aircraft, so extensive panel lines and rivet heads on wings are not accurate for actual combat P51 aircraft. Wings were covered with glazing putty to back over the thick part of the wing to fill the panel lines and rivet heads, the amount of panel lines and rivet heads visible varies with the individual aircraft, no two were exactly alike. All control surfaces had either cloth covering with detail, or aluminum skin with lines and rivets. Detail on fuselages varied by individual P51 planes. Engine cowling detail was always visible.

rossmick

Great info, thanks. The lightest cloth I have found is .5 oz where did you get the 3/8 oz? The Polycrylic urethane works great, just never stopped at several coats - usually 6 sanded out. Never considered it for the wing, great idea. I think what I will do is stick the Monocoat back on and test fly, if all goes well will strip the film off and redo the whole wing.
Looks like your 51 is coming along nicely. Too bad they don't make a P-51D fiberglass fuselage for this wing.

sjhanc

My Feedback: (3)

rossmick,
I bought mine from a bulk supplier 10 years ago, before I was on the internet so I don't have a sales record I can easily find. The glass roll does not have any manuf. label on it either. .5 oz glass is close enough, the difference in finished weight would be small. If I can find any info I will post it. I do have some .75 oz cloth from hobbico and the difference is obvious. I have always been on a light weight construction kick for my models, it seems to pay off in better all round performance, especially top end speed and low stall speed. I don't think it makes alot of difference in repairs to an already built model but now that I have given up on ARF models I will be doing more of the plans built types. I have plans for the Ziroli P51 and he does sell a B model fuse for his wing. This is a heavier gross weight model and my back and foot problems limit my ability to carry them.

I have a damaged H9 Mustang wing that is a close fit to the B model glass fuse's wing saddle. I think the H9 wing could be modified to fit but the dogleg part of the leading edge is different between the A-B-C models and the D model wing, the mods would be in redesigning that area for the fit. Changing the B's turtle deck to a D style deck is possible and it might be easier to change the B fuse and wing to D type. I'm lazy and would rather buy a kit with all this done for me. The TF P51-B kit was originally released with the D model wing profile, then later re-released as a D model kit with a B mod kit available, but still using the D wing. Counting the ARC version TF used the D wing on 4 different kit and ARF versions. I have seen fully detailed out TF B models competing in scale competition with no mention of the incorrect wing profile. This would be OK in the sport scale class but I think it pushes the rules in the Master class. The practice of letting the master flyers/builders enter their old planes in sport scale runs the novices off, you need to win or place to get into a regional scale event and the guys in the higher classes hog all of the limited spots in sport scale with new planes in master class and their old planes in sport. No room left for beginners to compete.or get started in scale.

rossmick

Been busy with other duties, but got wing closed up, servos installed and gear doors trimmed to fit. Look to fly it next week after I get it balanced. I will weigh the wing, and if anyone has an interest, please let me know what your wing weighs. I'll also weigh in the total plane and see if I have removed some of the total weight.
Thanks for the info on the fiberglass, 1/2 oz seems the lightest now. I am not certain just how much strength that light weight cloth will give to the wing, but I'll bet it will sure look great.
I agree with you, like any sport, the few take away the fun and enjoyment for the rest. It's been my experience that the IMAC folks are the most unfriendly and down right rude. I have just been through a very bad experience with the politics of our club and all I want to do right now is get my cost per landing under $100 for all the money and effort I have given to this club. I won't make that mistake again.

sjhanc

My Feedback: (3)

We have a good realtionship with the IMAC guys in our club, they practise all the time but are happy to let others have sky too. It was this way when I joined the club, I guess they worked it all out long ago. I'll go out on sunday afternoon, the day they do their most flying, set up my plane and wait my turn. They'll come over and insist I fly next. I fly a race track pattern and they fly the middle, so there's little interference. I go to one of their meets once a year to watch, they will have 2-4 planes in a little box in the middle, all doing aerobatics. They never have collisions or crash.

Your wing looks much better.

fujiman

My Feedback: (133)

Sad that cubs sometimes are too political in nature. I FLY FOR THE FUN AND PLEASURE OF IT!!!!!!!! I joined a cub so I can use the field only not fellowship. I get that other places. Fortunately the guys in my cub are very corgile and helpful, a few not so much. love my planes and love to fly.

rossmick

fujiman
I am with you on now using the field to fly for fun, and I will endeavor to avoid the club, local and federal political talk. I look at this like making a bad investment in the market, once you realize it was a mistake, get out of it, move on and don't dwell on the money and time spent. If there were another club with the same facilities and distance to travel I would change clubs, but for now I am stuck. It is getting so bad that if you take a photo on the field the club's bylaws now say that the photos belong to the club, no idea how they will try and enforce that one especially with cell phones . I even wonder if it is legal. They did get stopped temporally on the one that says if you bring legal action against the club board you are automatically dropped from the club and must be reinstated at a future meeting, attorneys are deciding that one. It is crazy land out here.

sjhanc
I can't say every IMAC flyer is difficult, but as a group it has been a bad experience, maybe it is due to the competition stress, I don't know . Glad your fellow members have more humanity and respect than the people I have dealt with. Enough about people.
Manual says flaps down 2 1/8" at wide end, Now with the slotted flaps, I thought I would set them where the flap leading edge lower face is parallel with the trailing edge of the wing for proper air flow, any thoughts? First time I put them down ought to be interesting.

Colin_Mc

Tail retract in and doors painted as bare wood just didn't look right.

Closed up the surgery from fixing the wings and then just the main retracts to fix with parts from Robart waiting for me in the US. Might even get to glue the wings together when i get back!

sjhanc

My Feedback: (3)

rossmick
I don't think the size of the gap is critical, just so left and right inboard is the same, and left and right outboard gaps are equal. I equalized my gaps, but never experimented with more or less gap. the wing is probably more sensitive to an unequal gap at the out board end of the flap's airfoil

sjhanc

My Feedback: (3)

rossmick
My TF wings typically average a little more than 8 lbs with the airscoop attached and the LG and servos. I don't have one with all the equipment mounted right now but I have two modded wings on hand withput any flight gear, one weighs 5lb 10oz with the air scoop, the other is 5LB without the scoop. my scoops are modified to be removable so are heavier than stock, plus I think the one scoop is a Fiberglass specialties product and may be a little heavier than the TF.
Add 2 llbs of LG and .5 lb for servos puts the 5lb 10oz wing at 8lbs 2 oz. I hope this helps.