Love the idea for rolling the foam 👍
Not sure if I mentioned it or not on my thread, but I used an arrow shaft for the forward fuselage
Love the idea for rolling the foam 👍
Not sure if I mentioned it or not on my thread, but I used an arrow shaft for the forward fuselage
That looks great! Do you have any idea how much it weighs right now?
Yes, I posted an image here;Did you ever figure out where the CG was with your models?
Yes, I posted an image here;
https://forum.flitetest.com/index.php?threads/sr-71-blackbird.61029/post-517364
Nice, are you gonna try to have it ready to fly by next weekend?After 2 1/2hrs chasing why the 1 EDF kept cutting out with really no pattern, found one of the wires that is soldered to the ESC that goes to the RX, was a poor joint. After doing it right, now I have a reliable setup.
Set up the differential thrust so now steps 1 and 4a are done. Working on setting up of landing gear, hoping to set up stearable nose gear.
Maybe even sooner.Nice, are you gonna try to have it ready to fly by next weekend?
Always interested!
Currently I had my exhaust down to maybe 85 percent (Ben H. Pretty much said I was probably choking the edf and should go no more than 90. One thing about Pringle’s cans is they have that nice slick foil lining.
I have to redesign my exhaust anyway, I might make them 100% (no taper)
I plan making cheater holes where the blow by doors/vents are. 😉
As this is my first real design using EDFs (and just so I’m crystal clear on this) you are referencing the fan face area, correct? That is the area of the fan blades minus the center spindle. I hope so, cause I spent a lot of time designing the exhaust using those numbers. 😂I have explored not only the exhaust area, but making improvements on the other end. I used a pitot tube, U-tube slated at 10 degrees to explore the exit area. Simply put, don't reduce it below 95 %.
What happens is the P static goes up inside and yes, the exit velocity is increased a %. In examing a problem, you also need to look at the other end, so as the blades turn,it leaks out the front. Yes, go from 5 to 11-12 blades and yes you improve it at the cost of a heavier battery.
Now, you also have leakage between the blades and housing. Guess what, the cheaper fans have quite a gap. Well, I ended up taking Scotch magic tape and layed 1-2 thicknesses between and reduced the leakage and it gives an increase in static thrust. Prove is, hold plane vertical and add power till it hovers with battery at full voltage. Check % of throttle on tx. Now tape, check same voltage charged and hold vertically. Found it took less throttle to hover. Even did this to just the EDF and improved.
Before, jet didn't take off from table, taped 2 layers and voila!!!
General rule for low airflow . If you choke the exhaust, yes, you increase the exit speed (anybody know what the foward speed amounts to?) but you then reduce the static thrust of the EDF.
I have done projects with my cheap 5 bladers with "thrusters" having 2 carbon tubes pick up total pressure and deliver flow to the wings as well as having a third carbon tube go thru the ducting for strength and have it fly a F-22 with no reduced losses. I do not choke the TV tube down at all. Another way I explored is as the guys came to the flying field, I watch the performance of the jets, ask what size the EDF was, and then measured the exit area. Result was between 95 to 100% the size of the EDF for the good performance jets and the other's had high reduction of exits. That's my experience.
This project has also layers of tape between the blades and housing.
As this is my first real design using EDFs (and just so I’m crystal clear on this) you are referencing the fan face area, correct? That is the area of the fan blades minus the center spindle. I hope so, cause I spent a lot of time designing the exhaust using those numbers. 😂
My first run was with the 5 bladed edfs, new build is using 12 blade. I have a thrust meter due to arrive any time so hopefully I can get some real numbers. If you check out my Alpha build maiden video, you can see she “almost” hovered....
I like the tape idea to tune the motors! Might give new life to those 5 blades.
Who’s the hater and why?!Here is vid of the SR-71 taxing. High winds were encountered.
Decided to punch to see power of EDF's.
Use Differential thrust for high speed turn.
Taxing using nose gear steering.