Corsair/Spitfire hybrid

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Will Aldridge, Oct 16, 2010.

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  1. Jan 25, 2012 #361

    Jay Kempf

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    VERY NICE!

    Belly outlet with annular inlet around spinner would be the best possible low drag setup. Actually, outlets near the max low pressure over the max thickness of the wing would be even better. You would have to have a weighted door up high in the top of the firewall to let the cowling shed during a hot shutdown. That door would close with any amount of forward motion or when you start the engine.

    Looks like it was born for a radial :)
     
  2. Jan 25, 2012 #362

    revkev6

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    it starts to look alot like an ar5 with that nose. from what I've read about the design process he was really designing to the exact thought process you are. "I want a neat looking single place that looks like a wwii fighter and is as efficient as I can build it"

    I like it!
     
  3. Jan 25, 2012 #363

    topspeed100

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    How about the RADIALENGINECOMPANY's 3 and 4 cylinder radials ?
     
  4. Jan 26, 2012 #364

    Will Aldridge

    Will Aldridge

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    Glad you all like it. I'm still wondering if I do or not. In any case none of the radial engines i know of would fit under it, it would still be a rotary.
     
  5. Jan 27, 2012 #365

    Will Aldridge

    Will Aldridge

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    Well I didn't like the first version of the Radial cowl and I still don't like the radial cowl as well as i like the P-51 style cowling. But form follows function and I needed more room for all the stuff that's coming with the rotary, so I revamped the whole front end of the plane and re-profiled the canopy. Still not entirely finished but I gotta admit i think it looks pretty good. I know none of you could see from the first rough concept but that cowling was not nearly as curvaceous. One other added benefit was that since I raised the profile of the front deck I also get some more room in the instrument panel which was tiny. Now it's just small.
     

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  6. Jan 27, 2012 #366

    highspeed

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    NICE! I've always liked the look of your design, but this is the best yet. Now it looks like a fighter and not like some 'sportplane'.
     
  7. Jan 27, 2012 #367

    Darren finlay

    Darren finlay

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    Take a look at the Supermarine F7/30
    ]
     
  8. Apr 2, 2012 #368

    Will Aldridge

    Will Aldridge

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    I have been taking some time off this project lately to work on another project, but i saw one of Mark Calder's (aka planebuilder) posts about his Robin Ultralight and using the seat from the Jantar glider. he was kind enough to provide me with the cad drawing of his seat. Amazingly his seatback angle was almost exactly the same as mine. Given that my seat is mostly behind the main spar and his is in front of his spar I had to raise the front of my seat to clear the spar but I still think it will be a comfortable position. Both Mark and I are the same height so that prompted me to take the dip out of the bottom of the seat since he already has a plane built that he knows fits him and our cockpit dimensions are very similar. That now gives me room under the seat for an aft spar to go all the way through the fuselage. The green seat is Marks and the yellow outline is Oscar, Marks dummy. I think I drew mine a little big maybe but I wanted to make sure there was enough room in the cockpit, and now I know there is.
     

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  9. Apr 3, 2012 #369

    GarandOwner

    GarandOwner

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    How are you going to route your controls? It looks like you might have issues with stick clearance based on your seat/spar location and the location of your stick in the picture
     
  10. Apr 3, 2012 #370

    Will Aldridge

    Will Aldridge

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    Depends on if I decide to go with pushrods or cables. I have room under the aft spar to run cables and I guess I could run a pushrod under there as well. Until the latest design change there was a torque tube coming off the control stick mixer going to the right side of the plane with a bell crank on the end of it that would connect to a pushrod. That's gone now, but I can think of about 3 different ways to route my controls back there. The design is still fairly fluid so a lot is going to change.
     
  11. Oct 19, 2012 #371

    Will Aldridge

    Will Aldridge

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    Now I can make airplane noises

    Finally got around to mocking up the cockpit. Obviously there is still some work to do but I'm happy to say that I fit in it about the way I imagined when i drew it. If as I remember someone telling me earlier in this thread I believe that a seat back parachute is 4 inches thick then i have plenty of room. The 2 chunks of 2x4 attached to the top of the seat are spacers to help simulate the parachute. Still don't know exactly what I want to do about a headrest but now i can see if I have room for the stick and so forth, and of course now I can make airplane noises.
     

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  12. Jan 20, 2013 #372

    Will Aldridge

    Will Aldridge

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    I'm incredibly dense sometimes

    I've known about the WAR replica Corsair for a long time. I was even aware of how the main wing spar was shaped since I used it as the basis for my composite design. But despite the fact that my design and the WAR Corsair are very similar in size, weight and performance it never occured to me that just maybe I should think about using it's wing as the basis for my design.

    I've heard nothing but good things about how strong it is. Ok, there's one complaint against it and that is that it's overbuilt. But supposedly that overbuilt spar has saved a couple lives in crashes so I guess it's a wash. I have wanted to build a one piece detachable wing (the WAR wing is 3 pieces) and I guess it could be redesigned but it would save me some complexity if the center section were permanently attached to the fuselage. Since I'm not planning on retractable gear there will be places to get rid of quite a bit of weight.

    So if anyone has a set of plans laying around unused and for a better deal than I can get brand new I'd be interested.
     
  13. Jan 20, 2013 #373

    Will Aldridge

    Will Aldridge

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    I was fooling around with the model and accidentally changed the color of the layer the skin is on and came up with this:
    yellow.jpg

    Can't say I've ever really been a fan of yellow but I really liked this (yeah I know it's more orangish than yellow). Maybe add some grey like in my avatar and I think it would look pretty good. The one question would be if this color is too dark? I figure the grey would have to be a lighter shade than seen here but I have seen a long ez I think with a yellow and grey scheme that looked pretty good.
     
  14. Jan 21, 2013 #374

    Will Aldridge

    Will Aldridge

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    I'm getting pretty excited about the idea of using the WAR Corsair's wing for my plane. I always knew that it was going to be the hardest part of the whole project and a lot of people told me that multiple times each.

    Well I had a 3d model of the F2G Corsair that i created so I scaled it to 1/2 half scale of the real thing to replicate the WAR replica and overlaid it on my design lining it up at the leading edge of the wing root. I think that the War replica probably had the tail volumes increased to account for scale differences (note that this is the Super Corsair that had a 1 foot extension on the vertical tail so the drawing is probably similar in that regard) and if my model is anywhere near accurate they would have had to increase the diameter of the fuselage to fit an O-200. Aside from that if they were accurate in their depiction of the wing then my wing chord at the root is within millimeters of what theirs is and it will almost be a plug and play situation. I know it won't really be that easy but I'm a lot closer than I was before to having a safe design.

    And if I really get crazy there is provision in the design to add retractable gear, which I have always wanted but know will add a lot of weight that i don't want.

    I am a little worried now about the engine. The rotary is probably 100 lbs heavier than the O-200 and as you can see my prop hub is almost a foot ahead of the Corsair's. So I may be adding weight in the tail which doesn't thrill me but since my plane is longer maybe it will balance out enough that the amount of lead added will be minimal.
     

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  15. Jan 22, 2013 #375

    deskpilot

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    I've been following your thread with interest Will. Nice idea and modeling. Have to say though, I think you fin/rudder is a tad too small. Not much, but larger would be better IMO.

    Whilst people rave on about the Spitfire and it's 'beauty' (I'm an ex Brit and have work on them) I'm so bored with their comments. I really like the Gull wing, so 'menacing'. The combination of the 2 wings really is a good choice, again IMO.
     
  16. Jan 22, 2013 #376

    Will Aldridge

    Will Aldridge

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    Thanks Doug,

    It's nice to hear some feedback. Admittedly I let this thread atrophy somewhat but I hit a brick wall. My knowledge and study had to catch up a little. This thread used to have a 5 star rating, and although the rating doesn't mean that much to me as far as weather or not the project should continue that and the lack of posts have made me wonder about continuing this thread. I'm open to any constructive criticism. The design has evolved considerably because of it and I hope more will be forthcoming.

    Regarding the vertical stab, the aspect ratio might be too low (Autoreply pointed that out) but the TVC of the vertical stab only counting the portion above the H-stab and not counting the leading edge extension or the strake underneath is .04, which according to Raymer is about the average for homebuilt aircraft. Of course adding in the rest of the surfaces will increase that number but I don't know how to calculate that. My horizontal TVC is about .7. So I think I'm probably good there.

    I have started on the construction of a 1/4 scale rc model. So we'll see if that tells us anything usefull about how it will fly. If anyone knows what considerations need to be looked at in order to gather any meaningful data from a scale model I'd appreciate hearing it.
     
  17. Jan 22, 2013 #377

    starbird

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    Be mindful of the Re that your tail will fly at. Most R/C planes, even larger ones need a larger hstab than full scale for low speed control. Whatever airfoil you choose, don't expect a Cl of much over 1-1.2 clean.

    With a gyro/accelerometer, pitot system and servo logging you can produce strip charts and determine the stick fixed stability derivatives of the model. Its possible to scale the data to estimate the derivatives of the full scale plane. The model would need to be ballasted similar to that of your full scale for meaningful results. Having your model setup this way would also allow you to do stall/spin tests also.
     
  18. Jan 22, 2013 #378

    Aircar

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    Starbird - you seem to be up to speed on model telemetry or data logging , can you list any model sensors and data acquisition equipment in general that is available ? I would guess that now some type of GPS would be the most useful for measuring speeds and rates , I linked to some model data loggers some time ago but my boarder wiped out all my files and I haven't looked since then --there was discussion on another older thread about dynamic similarity and the limitations inherent in simulating full size behaviour --can't recall the thread title off hand.

    The effect of the inverted gull wing on stall and slipping behaviour would be my first area of concern --the Corsair and Stuka seemed to fly OK (Loving's Love being another bent wing ) but it must be really complex to figure out the local AoAs and so forth in the presence of the slipstream and the fuselage with a bit of yaw thrown in . Having a car top 'wind tunnel ' model mounted on a gimbal and tufting it to observe airflow (or even measure forces)--with the airstream courtesy of some fast car driving ,is the least difficult set up. Better to find out any 'interesting' aerodynamics as early as possible.
     
  19. Jan 22, 2013 #379

    starbird

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    I don't know about everything on the market, but I've been playing around with an ardupilot. The version I have is the older one with a daughtercard (apm2560+oilcan). It has a 3 axis gyro/accelerometer, gps, pitot, magnetometer, barometer, and I think 3 more adc ports for other sensors. The software is setup to run at 50hz, so you won't be getting very high frequency data without rewriting the loops. The gps updates at ~8hz. It can save data onboard, or send it through a radio (xbee or equivalent) to a ground station (laptop). Its designed as a full on autopilot, not just a data logger, so it has extra features like waypoint following, autotakeoff, autoland, a fly-by-wire (rate and angle limited) mode, or you can turn off the automatics and fly by hand. I picked the ardupilot because I have experience with avr micros and wanted something I could develop on easily.

    ArduPilot - DIY Drones

    These systems aren't a true INS. The little chips are just too noisy to do any dead reckoning with them. You can get rates and maybe angles, but not with enough accuracy to integrate into a position. Position information comes from the GPS, along with ground speed and ground track. Ardupilot assumes that sideslip is 0 and will use ground track to head to its waypoints. With these setups you don't have any way of knowing your sideslip or alpha with any accuracy. You need to either setup pots with vanes, which have their own problems, or go with a true air data probe. I havn't got around to trying any of those options yet.

    I've never used a car mount, but it would be really useful here. You could do force measurements on those also.

    You can also do tuft testing in flight by mounting a small camera on the tail or wingtip.
     
  20. Jan 22, 2013 #380

    Will Aldridge

    Will Aldridge

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    Thank you Starbird a lot of good info there. I assume when you say ballasted you mean more than just having the CG at the same point, as in put masses in where the pilot will go and fuel etc?

    I'm afraid I'm not very good at using computers for data aqusition, that's one area (of many) with computers that has always given me a hard time. But I guess I'm going to learn.

    I never really considered that I could do tufting tests on a model this scale. I did have in mind mounting a camera in the canopy so I could do some first person viewpoint flying.

    Again lot's of good stuff and thank you.

    here are a couple of pics of what i have built so far. I sliced the fuselage into 2 inch sections and cut them out of blue insulation foam. I'm going to finish cutting the sections today and glue them all together then sand and fill, then fiberglass the whole thing. I'm going to cut out the canopy and use it as a mold to vacuform a clear one.
     

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