Mig 17 & Vasa 55

[Dmerino]

I'm looking at building a Mig 17 out of 1mm depron. The length of the fuse. would be about 20.5" long. The Vasa fan unit at the exit is 2.18" dia. The exit cone on the fuse is only 1.62" in diameter, which is only 70% of the diameter of the Vasa unit. The estimated weight of the plane minus radio, servo's, battery, fan unit is about 5 oz. I know the exit diameter is smaller than desireable. Does anyone know what kind of thrust loss, approximately, I will be looking at? This bird is already getting pretty big and I think it could exceed the fan unit's ability to fly it. I would like to try and keep the exit cone as close to scale. If I make the exit cone diameter the same size as the exit dia. of the Vasa unit the plane's fuse will be 27.5 " long. This is too big, I believe for this small fan to fly. I am open to any comments. I am attaching a drawing of the proposed location in scale with the fuse.

Finally got the image to attach. Original file was too big. Thanks. Dennis

[Dmerino]

I finally got the image to attach. See original thread. Thanks, Dennis

[AirX]

Hi Dennis,

Just go with an exit of 1.75"diameter, will be a bit small for a speed 300 but will work and should be hand launchable if kept lightweight.

Cheers,

Eric B.

[Dmerino]

Here is a quick photo of the Mig 17 paper model in 1/32 scale. Final fuse. will be about 20"s long in 1mm depron. Dennis

[winmodels]

Hi Dennis

the way you have drawn the VASA fan you have not accounted for the reduced annulus (FSA) which would allow for an exit diameter of 48mm ~ 1.89" at 100%.
If you reduce that to 80% you get a diameter of ~43mm/ 1.69".
If I were you I would go along with your first suggestion of 1.62". There should be not too much of a loss. On the other hand I have not tested a VASA55 so I dont really know for sure. It's also a question of the motor power you have available.

Have fun with fans

Klaus

[Dmerino]

Thanks, Klaus. I am going with the original dimensions. Dennis

[mtflyr]

Hey Dennis,
Good luck. Your inspiring me to revive my paper to Depron MiG-17. My AUW was 7.5 oz. flew it about 25 times and you can see minor damage as the std. EDF-50 would just keep it in the air. I now have a brushless EDF-50 and with LIPoly's it should really fly well. I had great success with my two F-86's with the std. EDF-50 but with the MiG-17's wing sweep I guess it needs a bit more umph. So at some point I'll throw in the brushless.
My WS is 26.25" and the fuselage is 23" inlet 2" outlet 1.5"
I used the Osprey Book scale drawings of the MiG-17 enlarged for the wings & tail area and a paper model MiG-15 plan I had which I added 3" to the fuselage for it's fuselage.
Your paper MiG-17 looks good what model is it? It should go great I think an EDF-40/50 with the IPS sized fiego brushless and a 3cell Lipoly pack would fly a plane this size or a little bigger no problem.
Pete

[Dmerino]

Hey, Pete. It is good to hear from you. The Mig 17 is from Marty Modelarz Polish Mig 17. I think it is out of print, but I was able to download it from a Russian web site. The Vasa 55 has a ballbearing 300 motor. It is a little tired so when it goes, hopefully, I'll have a little "denero" to buy a brushless combo. Anyway, it will be a good winter build. My "George" is finished and will be printed in the next Backyard Flyer in the neighborhood watch section. I think I recall seeing your '86 in that section....Right or Wrong? Anyway, you have been my inspiration for a long time and I really appreciate it. I hope your boy is doing good with the C47. Peace, bro. Dennis