The body of the Marston Pterodactyl would have to be built from scratch with intakes under each wing, the fan approximately middle of wing, and exhaust rear of wing between a redesigned rear body and v-tail.
I was hoping the weight reduction from using 2 motors now to only one in the fan would allow me to cut weight and fly longer. The current setup requires full throttle to hand launch and at least half throttle to soar. Currently using a 3cell 1600mah battery under the head (easy to change leaving wing attached), I only get about 4 minutes flying. I was hoping the reduction in weight and redesign with more weight to the rear would allow me to balance it with a 2200mah battery under the head. I basically would be trying to do under 400 ft soaring with some looping and rolling.

Not sure what fan you intent to use, but what ever you go for as an EDF, it won't be as efficient as your prop set up, so it's probly waste of time unless you like just bit of experiment.

I really would like to use my 6S 4000mAh batteries from other models: Has anyone got some suggestions for motors and prop combos for a 2kg YAK54 (1400mm wingspan)? I'd like unlimited vertical but not stupid power, and preferably lower cost (from Australia, so Hobbyking and Bangood, or anywhere local).

Originally Posted by robmitch

I really would like to use my 6S 4000mAh batteries from other models: Has anyone got some suggestions for motors and prop combos for a 2kg YAK54 (1400mm wingspan)? I'd like unlimited vertical but not stupid power, and preferably lower cost (from Australia, so Hobbyking and Bangood, or anywhere local).

This is not a thread for questions about power systems - rather for sharing details about successful setups. If you repost the question as a new thread you'll get a better discussion and options. Be sure to include the max prop diameter that you can use with sufficient ground clearance.

My latest creation, "2B2", (two on top & two on the bottom, LOL) powered by four modified 50mm counter rotating EDFs to minimize the torque roll. This is just a little piddly proto experiment before creating a large 90mm version.
With the current hook up, running each pair of the power units on separate single 3S/4.5Ah/50+C , I'm losing considerable power (15-20%) compare to running each unit on separate battery pack, I'll hook up at later stage just to compare its performance.
Each fan runs off 40A speedy.
Peak current draw of individual unit is ~35-45A if running on top C rated packs at some 400-500+ watts.
Unfortunately model came up heavier than expected at 2.8kg with the aprx. static thrust measured at 2kilos, but should increase to over one to one ratio with the separate battery supply hook up.
After 6 flights so far off the sealed strip also grass it performs great, immaculate smooth, hardly audible at some distance.
After initial flying I have redesigned the frame by extending the nose section by 12 inches with added canards to check its pitch stability as comparison to the shorter original version.

Nice! 2B2 looks great!

Thanks Body, no problem flying off the sealed strip or dry low cut grass but my last flight couple days ago off the pretty wet field with slightly longer grass I had a battle rotating. Only thanks to few bumps it lifted off with bit of struggle holding on, not stalling it at such a low take off speed.
The tiny wheels is one of the problem after the wet weather we had but the wing load is pretty high to push it along with these tiny EDF units being limited in power with my present 2 by 2 hook up.
As intended I'm currently resetting each power unit to run on individual battery pack resulting close to 500 grams of extra thrust at minimal add on weight and just about the same current draw. The only draw back , I have to order set of four same capacity batteries to get the best out of it.

Easiest way to check the most successful power set up, after my initial 15 flights with the 90mm "Mercury" on 8S will be my next flying action, this time using "Jet Fan 90" on higher 10S voltage, and after I also give it a go with the good old "Wemo 90" on 8S to compare. Stay tuned for the results.

power system sucessful

Very much so, just about one kilo extra thrust from the rear after upgrade from 8 to 10S with the new "JF 90m" power plant. As expected, higher current draw but still 3-4 min flight time on larger capacity (5Ah) batteries set up as 6+4.
Now it really feels like flying a jet at some extra AUW.

Model: HANGAR9 P-51D RED TAIL (PTS) = Progressive Trainer Series 58-1/4 inch wing span (Glow -to- Electric Conversion)
Motor: SUPPO BL-3620/6 (840Kv)
Speed Control: HobbyWing 80-AMP ESC while using an external Castle Creations BEC PRO
Cell type/count: 4-Cells, 4,000mAH, 35C, Lithium Polymer
Prop/fan: APC 12 X 10-E
Reduction method and ratio: Direct Drive | 1:1
Amps: 48.3 AMPs
Watts: 693.2 Watts
RPM: 7956
Weight Read to Fly: 6-lbs.
Comments and links to other forums for more info, video, etc.
https://www.rcgroups.com/forums/show...n#post46111027

3rd flight of my HANGAR9 P-51D Mustang (58 - 1/4 inch wing span):

3rd Flight of the Hangar9 P-51 RED TAIL PTS 12-15-2020 (7 min 8 sec)

One of the most successful small model in my fleet is "HK Skipper", flying for the last 7+ years, now with close to 1100 , 3-5 minute flights in the log book. All but (3 flights-by hand launch) off the water.
This one is the oldest of the 3 models, including XL version.
My lasting success comes after some 12 major improvement mods all detailed in the build log in water plane thread.
Pretty light model at some ~575g. AUW with the 3S/1800 /40C pack, the stock motor spinning custom made up -cut down APC prop 6&3/8x5E.
250-300W at 25-30A current, subj. to battery C rate the model performs like a dream to date.
Just about daily flier while having bit of exercise paddle, latest footage this morn in ideal calm conditions, enjoy.

2020 1229 141437 018 What a day! (4 min 54 sec)

Another rarity EDF jet of my fleet, highly modified not only frame-wise, but power-wise with its unique only 4S powered 90mm EDF unit off the 80A speedy.
To reduce the current draw I have cut out 3 of the 12 impeller blades spaned by the "Emax -36/60", 1650kv motor. Running off the 4S/2.65/45C pack it pulls some 2.2 kg at some 35-40A/550-600W.
At 1250g. AUW, it is pretty lively flier, either off its simple removable landing gear with steerable nose gear, or off the catapult launch, as my preference.