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lelievre12 last won the day on November 17 2020

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About lelievre12

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    Peter Le Lievre
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  1. The SQ2000 factory fuselage was not an advanced mould. It was simply a 'tube' in two halves with no door cutouts, windows, strakes or any other detailing. All this had to be added manually which makes the benefit of 'factory' moulds pretty small. It would be easier and better to CAD up the design, add the window/door/strake detailing and then CAM cut the mould in foam. You can see more at SQ2000.us See these photos: finalresult-flattened.mov
  2. Wow those IGUS bearings look really nice. Ordered two.
  3. Here is a shot of the Lancair IVP trailing edge with that flat cutoff. My recollection was that it was 1/4" to 3/8" On reading some IP (Wainfan Patent) https://patents.google.com/patent/US4867396A/en?q=Wainfan+micro+flap&oq=Wainfan+micro+flap it seems as though the more aggressive cutoff on the trailing edge is more about transonic stability than low speed drag reduction. Something I guess a Lancair might worry about but less so for us!
  4. Kent, thanks for the reply. I will check the wing next time I am at the hangar for reflex on the underside. The N416 wing was foam core (like a Cozy/Eze etc) however my kit came with the alternative molded wing (Lancair style with strakes and no core) and the trailing edge is pretty fat. I think what I will do is bond a 0.5mm strip of carbon on the top edge then flox under to fill the edge. (whilst the wing is upside down). The idea is that the carbon will keep the edge resistant to nicks and hangar rash despite the thinner edge. I am expecting that a feathered edge will be less draggy but read that "Harry Riblett said something about cutting off the trailing edge at 99% of chord length is better than a point for the airflow." so this is confusing me a little. I know that the Lancair IVP I flew certainly had a squared trailing edge that was around 1/4". However my hunch is that this trailing edge is there to reduce high speed aileron actuation forces rather than to reduce drag.
  5. I am finishing my SQ2000 project which has molded (not foam core) wings. The 'as molded' trailing edge on my main wing is a pretty fat radiused edge which is ~1/4" radius (1/2" top to bottom). Looks draggy indeed. Looking at the Eppler 1230 design I see that the trailing edge is 'sharp' so the question is "what trailing edge are other folks using" on their Eppler main wings? I am inclined to fair the rounded edge to make it sharper perhaps down to around a flat aft face/edge of around 1/8". I could go even sharper perhaps by using a thin carbon undersheet with micro to fair the top edge. I would have thought the sharper the better but not sure. I have seen a more blunt edge say squared to 3/8" like a Lancair? Any advice appreciated.
  6. Marc, thanks for the reply. I hadn't read of Whitcomb but have now. Its interesting to note that the 'Typical' winglet sections have outward incidence "i.deg". In Whitcomb's work, this is quite pronounced (7 degree) at the root of the winglet and still 4 degree at the top. I haven't seen this measure of either twist or incidence in any canard wings to date, unless I missed something? Its also interesting to note that the winglet is canted 15 degrees, which again you don't see in canards. Finally, I see that the lower winglet incidence is set to 11 degrees and 36 degrees cant. This seems a lot but makes sense when you think about trying to 'untwist' the vortex before it happens. Your text about full chord lower 'slab' winglets is exactly as I thought. I did read Nat Puffers explanation of them adding "at least 1/2" of aft CG" and I was planning to add them. It seems another example of how the early Velocity SE and SQ2000 designs didn't make the leap from 2 seats to 4 seats very well (like Nat did). However, despite what Nat did, I'm wondering to what extent the Whitcomb 'mini' lower winglets are as effective as full chord. I haven't yet found any data or flight reports but will keep looking. I wonder if Nat tested them? It would seem that an 11 degree incidence lower 'Whitcomb' winglet is attempting to be as effective as full slab (and probably will have the same drag!).
  7. I see these lower 'mini' winglets on older Vari/Longeze. I'm sure there is a long history of discussion about them. Can someone point me where I can read more? At the moment I have only upper winglet/rudders (Berkut/SQ2000/ERacer style) and wondering about the tradeoffs the between nothing, 'mini' winglets and full size lower winglets Cozy/Velocity style.
  8. I think the big issue with retracts is the additional weight. Weight kills speed so aerodynamic gains can be diluted by increased drag from a heaver wing loading. I have to agree with others who prefer fixed gear. However if retracts can be made lighter then the advantage creeps back. I already have Infinity Retracts on my project and just the stock hydraulic pump and solenoids weigh >10 lb. Not including wiring etc That is sooo heavy. . Looking at the history from Lancair etc these old pumps are straight out of your outboard tilt lift from the 60's and migrated to aircraft at some point. Not exactly ideal. Since I have the retracts I am keeping them, however I plan on trying a state of the art BLDC hydraulic pump (brushless DC) which weighs 0.9 lb in an attempt to cut weight from the installation. Here is the current installation. Ill update when I have the new pump installed. The goal here obviously will be to have my cake and eat it too. I
  9. Sheesh. Of course! So the cabin air ends up exiting via the spar. I should have noticed this when I was looking at my airframe. Thanks for your help Andrew!
  10. This is the kind of thing I am thinking of. The rubber 'flapper valves' let air out when pressure builds inside the cabin. Not as big as this air pressure vent from an F150 but same principle.
  11. The reason I ask is that the cabin doors are big and any pressure increase inside will lead to a huge burst load. Even 1/4psi over a 36” x 20” door = 180 lb pressing out. I fly a P210 with a 3.35psi pressure diff and the door locks are super heavy to cope. Given that quite a few canards have had doors fly open in flight I’m going to positively manage cabin pressure to ensure it doesn’t increase at all. Even a slight increase will cause to hiss and this is the door flexing outwards until pressure can escape. Noisy and far from ideal.
  12. I am wondering what folks do regarding letting cabin air back out. I have arranged my inlets just fine but cant see any info in the build about how that air is getting out again! Pics/hints appreciated!
  13. I have a set of them on my SQ2000 project at KVDO if you want to see them up close. Not selling but happy to send details/photos etc. James at Infinity is very responsive so simply email JD@infinityaerospace.com
  14. For those interested in the inside of a Thieliert TAE125 (now Continental CD155) here are some photos of a gearbox removal and clutch check. The engine is out of my SQ2000 project described elsewhere. The TAE125 engine is based on a Mercedes OM640 engine however it is heavily modified with custom aluminium block, custom sump, flywheel and fuel injection. The gearbox exterior looks conventional for a PSRU with the exception of the hydraulic propeller controller which includes an oil pressure pump and ECU controller governor. Propeller flange is a Rotax style 80MM PCD suitable for constant speed MTU propeller. The gearbox is removed via the peripheral M8 hex capscrews and two M5 screws just below the propeller flange. The flywheel is then revealed which is custom Thielert (not Mercedes O640) The flywheel still contains a clutch plate which drives the gearbox. The design is arranged to absorb the power pulses from the high compression Diesel via slippage of the clutch plate. Many Thielert failures have been caused by the plate either slipping (oil or contaminant) or burning. The design differs from other PSRU (eg Rotax) which normally retain a flywheel and rubber power coupling which is used to transmit power. As the engine has no clutch pedal, the clutch plate is permanently retained by a twist locking ring. To remove, the clutch spring must be compressed by inserting 4 specially slotted M8 screws. Once the screws are in, the clutch plate can be rotated anticlockwise and released. The clutch plate and clutch can then be removed and inspected. Once the clutch is out, the flywheel can be seen. Its clear it is NOT standard Mercedes and is a custom lightweight flywheel made by Thielert. Later Continental CD155 models have a dual mass flywheel however these earlier engines have a conventional 'single mass' style. The clutch spring itself is a giant Belleville washer. Not individual springs. Its marked with it KN setting which is important in the correct 'slippage' for the clutch. The clutch plate is conventional Sachs although it is marked with a TAE part number so perhaps the friction material is custom. Looking at the gearbox side it is a standalone PSRU with conventional spline to mate to the clutch plate. From the above dissembly, its clear that Thielert have customised the design of the drivetrain extensively to reduce weight and account for the high torque of their Diesel motor. The PSRU design is unique in many ways and illustrates the difficulty of engineering a PSRU with a high torque engine.
  15. Yee Ha! Discussed here: https://ww2aircraft.net/forum/threads/the-what-is-it-game.25244/page-461 Apparently the South African one was not 'genuine' Richter. It was a https://en.wikipedia.org/wiki/RMT_Bateleur "Actually, this is not a Richter Delta Dart II, but it is merely an empty hull and wing-structure of a plane called "Bateleur" which was built by a man known as A. v. Schoenbeck. It was a case of blatant plagiarism - the plans were obtained and illegaly used in the attempt to establish production in South Africa. In South Africa everything ended in a major case of presumably fraudulent bankruptcy. The single authentic Richter Delta Dart II remains in germany, its whereabouts kept secret." Video of the Bateleur here: Now that design is going to have some serious pitch over on throttle up. Marc Z?

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