RedBaron

13/02/2014 - Are Jet Provosts shy? Prior to starting on the exhaust area I thought that I would look at a few JP rear ends to set the details in my mind. I have just spent some time looking at literally 100s of JP photos and find that they do not like having their afterworks photographed. I really only found three pictures that were helpful, they do show that there are some variation in this section of the aircraft. So depending on the specific aircraft that you have chosen to portray you may want to check the details for yourself.     Edited By RedBaron on 13/02/2014 15:17:07

Thanks Andy very interesting. I had to make a slightly bigger adjustment, but I have now checked the wing and tailplane incidences and they are just fine. RedBaron

11/02/2014 - I did not make any progress this weekend or today, but I did keep popping into the hangar to contemplate the rear fuselage and develop my work list to tackle this: Before I finish the top and bottom sheeting I need to fix the lengths of the elevator and rudder snakes, install their supports finalise the exit point of the rudder snake. Then there is the fiddly block work to get the rear end looking neat and also the jet orifice. The fin parts when glued together will need to be removable for final shaping of the rear parts. I suspect that the very rear end will need to be painted, I can't really see getting film covering to work well here and look nice. I can begin to feel the work list coming together but have not written it down yet. It is a job for tomorrow morning, to get it into my NoteBook. One matter I can't make my mind up on yet is which hinging method to use for the elevators, maybe Andy and those who built the JP earlier might tell us which methods they used. Having had my first contact with indoor building and flying I am somewhat taken with glue-line hinging for small models and I think this will do well for the rudder. This method has been just fine on my Phase 3 U-2.

Andy, it's just one small thing (but interesting). Maybe it is like all those beautiful ancient Egyptian buildings and monuments, they were always left slightly incomplete or with a small error in order not to offend the gods by being too perfect. Best wishes, RedBaron

Thanks for your comments Andy. I have just looked at the plan again and still can't work it out, I suspect that the dowel cutout in the R1s does not match the plan?? Plus the small effect of dihedral also plays a little part. However no great problem and easily fixed. So long as the top surface of the wings fits exactly to the correct place in the fuselage sides (and mine does) then the wing incidence should be just fine. Thanks again RedBaron

09/02/2014 - Wing construction is now complete, except for a few minor things like do the under wing block work, fit the wing bolt ply plates, fit the little wedge at the inboard edge of the ailerons, adjust the working clearances for the ailerons and a final light sand.   Here is the wing at this stage:     And here is the wing actually bolted to the fuselage for the first time:   There are a number of points that I should make now: 1 The wing tanks - If you have not already glued together your wing tanks you might like to consider the following. I did leave out the central lamination to get the initial dimensions as close to the plan as possible. Now with the tanks carved and sanded to shape close examination will show that I have not been able to sand out all of the lamination lines. The reason is that without the central lamination the geometry of the remaining laminations does not quite work properly. This is no big deal, one might sand the tanks undersize to get rid of the lamination lines or fill and sand the small gaps which is what I will be doing. If you have not glued up the wing tanks do include the central lamination (as recommended by Andy) and just do a bit more shaping. 2 Bolting the wing to the fuselage - After inserting the dowel into the leading edge of the wing (unglued at this stage) I was surprised to find that I could not get the wing to seat properly. Not a major problem I just gently filed the lower arc of the dowel hole in F4 downwards (by just about half a dowel diameter) until the wing seated properly. I then made an appropriate hole in the rear of the wing for the wing bolt and as you see the wing is a very nice fit. Now having to ease a dowel hole is pretty normal but this kit has such a nice plan and such accurately cut parts I felt that I had to get to the bottom of this problem. A cup of coffee was needed to encourage the two brain cells to come up with the answer, I think that this is the explanation: Very early on in the build one of my first jobs was to fit the triangular sections to the top and bottom of the fuselage sides. As we often find the triangular dimensions are rarely accurate. So when I came to fit the formers I had to adjust the diagonal edges. Lacking care here F4 ended up a little high relative to the sides, I remember having to sand the top and pack the bottom of F4. I did not think about the dowel hole at that stage! So if you are still at an early stage do check that the dowel hole in F4 is correctly positioned relative to any chosen datum on the fuselage. If you do not get it quite right the solution is easy, but I did feel that I had let the designer down on this point. Well I guess it is back to the fuselage next. If you are new to this thread then please note that my complete NoteBook for this build is on SkyDrive, the link to it is given earlier in this thread. Edited By RedBaron on 09/02/2014 22:35:34 Edited By RedBaron on 09/02/2014 22:35:59 Edited By RedBaron on 09/02/2014 22:37:04 Edited By RedBaron on 09/02/2014 22:50:53

Thanks also to Tony for your comment. Not a silly question at all. I have in mind a x2 sloper but had not got as far as thinking EDF for that one as well hmmm. Best wishes RedBaron

Thanks for your comment Mark, the thought did go through my mind as I already have several slopers with EDF installed and flat field flyable as well. On the Flyers and Builders Forum (on Proboards) there is a build blog in progress now for a foam JP with brown paper covering (you do have to register on this forum to access even viewing) http://furbirdsmc.freeforums.net/board/24/flying-related Best wishes RedBaron

05/02/2014 - Fitting the wing tanks. Here is a picture of the port wing tip: The inboard half of the tank has been fitted to the wing tip stub, and hopefully you will be able to see the magnets for tank retention. Given the snug fit to the wing I felt that a pair of 6mm Neodymium magnets would do the job. If your local model shop does not have any try: www.first4magnets.com for great service. The holes for the magnets were bored with a piece of sharpened aerial tube and the magnets retained with cyano, I did do a double check for correct polarity! Well next I guess do the same for the starboard wing, join the tank halves and do a bit of carving. Then the wing and its works will be just about finished for this construction stage.

Here it is all connected up. Adjustment is possible everywhere to suit later. If you have not yet applied the aft fuselage top sheeting it is advisable to check that none of the works here interfere with the wing bolt retaining plate. Now to do all the wing shaping, I think that three wing templates will be needed to get that nice wing section into shape. Edited By RedBaron on 04/02/2014 19:32:58 Edited By RedBaron on 04/02/2014 19:33:37

04/02/2014 The aileron servo connectors: Again I was looking for a relatively simple solution with preferably no wire bending or soldering (not that I mind that stuff) but I felt that this approach might be useful for the less experienced builders. A search through my spares box yielded the stuff for my approach, shown in the picture below: Starting at the left: servo horn and pushrod connector; standard 2mm threaded push rod (needs to be shortened); standard metal clevis, but with the pin part removed with a Dremel parting tool (leaving a one-legged clevis) and lastly another pushrod connector to be screwed to the vertical aileron horn and retain the one-legged clevis. I hope the idea is fairly clear despite the poor focus picture. This set up will translate the servo arm movement from one plane into the plane of the vertical aileron horn movement. This approach would need beefing up for bigger models but should be just fine for the JP size.

Hi Steve, On clamps I went to B&Q and purchased four B&Q clamps about 8inches long, metal and plastic with softish plastic jaws. These cramp together by a sort of pumping action on one of the handles and also they have a quick release lever. Four of these allows one to do all sorts of controlled clamping on this project a little easier than the workmate. On posting the photo there is a lot of info in the Forum User Guides easily found at the Forum top level Best wishes RedBaron PS if you have a PSS day in mid April maybe some of us slopers in the south will come north for the day. Who has info on this please.     Edited By RedBaron on 03/02/2014 22:28:10

Thanks for your comments Phil, I was just thinking that at this rate your JP will maiden next week end No on Vortex I just followed Andy's lead and got mine from Petes Pilots. Quite solid but I begin to feel that weight will not be of prime concern for this model.

Hmmm, well RedBaron must admit to not noticing this instruction either.. And like Phil my web grain is classically vertical. For myself I don't think it matters a lot. If I was going to argue the point I would say that the grain of the skins provides the strength spanwise and the web with grain vertical holds the top and bottom skins together, thus completing the "D" section at the front of the wing and it is the "D" section that gives the wing its strength. If the web grain is horizontal possibly that might invite an unnoticed spanwise crack in the webbing and so destroy the integrity of the "D". I think that it would be hard to aerodynamically stress these short wings to breaking point. Also models are designed to fly not crash. If one does crash one does want something simple to break thus absorbing the energy that does have to be dissipated.

02/02/2014 See JPWeenieWashoutWedge section of my NoteBook for details of top skin. Now that the top skins have been applied to the wings I felt that I had got to the stage where I wanted to perch all the parts together to get some indication of the finished model and here it is: Lots still to do but at least the JP character is beginning to emerge. I think that I will now continue with the wings, installing the servos, making up the pushrods, fitting the l/e stub tips wing tanks etc.

01/02/2014 - More stuff: Here are some practical suggestions for the WWW for those who want to skip my theoretical observations these being completely optional: I decided that my wedge will run effectively at the position of the torque tube ending as per plan at the outboard end of the aileron cutout. Now cutting a wedge 18 inches long tapering from .8mm to nothing is clearly possible. However measuring .8mm accurately would need a lot of care. Measuring a length of 1mm is a bit more attractive and if the wedge is 22.5 inches long we get the same angle and can use any 18inch section of it. The next stage of my thinking was to cut a 22.5 inch long wedge tapering from 1mm to 2mm this will do the same job but avoiding the possibility of runout of the knife as one approaches the end. This worked just fine Laying out my plan on my really flat building table, I covered it with transparent kitchen paper. Starting with the port wing, I pinned the outboard thick end of the WWW in the correct place, positioned the inboard end and tacked it to the paper with a small drop of Cyano. Small balsa blocks were pinned to the board along the l/e, tip rib and t/e. The top skin was cut about 1mm oversize (aileron to be skinned separately). A small cut out was made for the aileron horn wire and the root end of the sheet lightly sanded slightly concave to fit exactly along the port R1 The sheet in front of the spar was lightly misted with a water spray PVA was run over all the surfaces due for glue. The top skin was positioned along R1 and along the t/e and pinned at the t/e Using a ruler the skin was pressed down up to the main spar where it was pinned in a number of places and then moving forward gently pinned to the false l/e. Many weights were applied to ensure contact with all the ribs. This all went pleasingly quickly. So time for a coffee whilst the PVA really sets to full strength. There is more detail in the NoteBook on SkyDrive in the JP WWW (Weenie Washout Wedge) section. I have decided to leave my aerodynamic notes on washout and tip stalling (much better called "incipient spin") in the NoteBook and not put that stuff here.   Edited By RedBaron on 02/02/2014 00:00:39