30inch Herr pitts special - RC Groups
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Mar 28, 2016, 04:03 AM
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Video

30inch Herr pitts special


hi this plane has been done before on here but I thought I would throw mine up any way because Im really happy with it.
Its my first bi plane
its my fifth pane
and the third I have built.
I stuck mostly to the plans but did some lightning as per what most people do check out the first vid.
HERR engineering Pitts 1/2A aeroplane rc electric conversion (11 min 1 sec)

details in the vid commentary.

Landing gear was a I think different to how most people do it and it works great, details in second vid.
Herr engineering sig mfg pitts special flight review (6 min 16 sec)


Flying vid of the 12th flight, I chopped out the 2:30 after take off because I was just flying about getting used to filming and flying.
but from about where it cuts back in I have deployed the spoilerons which made a huge difference. from about 1:50min I am flying about 25% throttle and pretty much full up elevator 2m off the ground, you can see it chugging along with its nose up in the air until I pull throttle back a bit to loose height and land it.
HERR Pitts special-40%spoilerons-15%up elevator (2 min 41 sec)


One question: on the flight in the video I mostly cruised around under half throttle with about 1min of full throttle aerobatics and total of 9min flight time, the battery only took 850mah to charge up and its 2200mah battery the most the batterys have taken to charge is 1100mah but they where getting noticeably weaker on the flights that took 1100mah.
Would it be worth trying a smaller battery to save weight? Im happy with 9min but wouldn't want any less and preferably 10min which the next flights will be set to.
Any battery size and make and where to buy recommendations.
Plane weighs 770g ready to fly and the battery's weigh 175g

Thanks
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Mar 28, 2016, 07:16 PM
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numb_thumbs's Avatar
That is really nice!

Now see I am happy with 5 min flights so I would lighten it up but what about C.G.? Can you take the weight off and be OK on CG?
Last edited by numb_thumbs; Mar 29, 2016 at 07:15 AM.
Mar 28, 2016, 07:28 PM
Registered User
HI Numb thumbs, pretty sure I could keep the CG o.k it may mean having the battery entirely inside the fuselage because the plane came out really nose heavy, but it wont be impossible. I like 10min + flight time because I have 3 batts and it means I can be at the park for 40-50 min which makes it worth the drive down. if I had 15min fly time and 40min of round trip driving to do it I probably would get out les than I all ready do.
my HZ champ has one 300mah battery and I fly that for 15min by itself with no battery changes makes it more efficient on time at the park.
My airsail pt19 flys for 10min and is another of my faves.
but my Eflight yak54 flys for 5min and I don't fly that so much anymore because of all the batterys to charge after every use.
MOstly want to know if say a 1300 3s or 15003s based on the 9min flight times and 850mah-1100mah energy use would allow me 9-10min flights and save me on weight because shes a tad on the heavy side.
Either that or I could just fly for longer on the 2200mah which I may do now I have it flying slow enough.
Thanks
Mar 29, 2016, 08:39 PM
Registered User
Herr Pitss 30inch-Mixed flying in 11-20 knots wind (6 min 58 sec)


Flew again today, got vid of the second flight, it was windy and my first time in the wind with this plane so its wasn't the best flying for the camera.

Once in the morning all slow flying and flew for 12min need to check the battery usage.

Again at lunch time and flew for 11min but much higher throttle even full throttle for long periods and the battery didn't seem to run out of power by the end of the flight. the battery was only just warm to the touch and the motor and esc where cold.

Might try an 11x6 3 blade prop to see how that goes.
Mar 30, 2016, 03:18 PM
Registered User
Batt usage
13th flight in the morning no wind 1000mah
14th Lunch time flight in video above 1100mah used
15th flight after work higher wind again 50% full throttle batt used 1900mah.
This last #3 batt has puffed a bit even though it finishes the flight barely warm.

Aileron response in the high wind was average had to pull out of rolls after just starting them because it was rolling so slow and loosing so much height.

Practiced cross wind landings and all two went well.

Practised landing a lot into the wind all 10 landings went well.

one major problem with the model is the interplane struts, both have popped out now and have punctured the lower wing covering either side I will have to fix this yet to be determined how and I will post it up here when the issue has been resolved.

I will also seriously consider installing ailerons on the top wing, if I do I will also post it up.

Thanks
Apr 01, 2016, 05:03 AM
Registered User
Herr pitts special 30inch mods (2 min 42 sec)


Interplane struts modifications. will try put it in the air this weekend to see how they hold up and how moving the cg back a bit helps with landing speed.
Apr 06, 2016, 03:45 PM
Registered User
Flew this morning after missing two previous perfect mornings with no wind I decided to fly regardless of the high wind.
Flight time 7min-flight number 16-the wind had an average wind speed of 23km/h I guess gusting up to 30-35, it flew well it required minimum 3/4 throttle to head into wind and had to be pulled back on the down wind. hard to tell if the cg moved back helped much because of the wind but it was rolling at just over half throttle into the wind
First landing was a hard one at just under 25% throttle, with no issues the interplane strut mods held up well. 2nd 3rd and 4th landing all good.

Spoilerons up before final turn to get the plane settled in,
final turn,
cut to zero throttle to get it to drop steeply into the landing zone
4m off ground increase throttle up to 30% to make head way into wind and steady the plane in roll and decrease the approach angle-
gentle gentle flare, to much and it would float on and not touch,
After touch down cut throttle asap and give full up elevator asap to stop the wind trying to flip it over.
all gave a silky smooth landing.

Weirdly this plane and I struggled with takeoff in wind far more than landing in wind.

apart from buying new higher c rating batterys and pushing the cg further back this plane is signed off as tuned and ready for continuous use. I would make the wind cut of at gusting 20km/h to make it a reliable flyer with me at the sticks.

it is my most versatile plane so far as it can fly in wind, take off from grass, fly slow, fly fast, do aerobatics.
And to sum up the gas to electric conversion and close the thread.

Awesome little plane,
easy to build
easy to fly,
robust,
looks pretty good
easily transported ( had it riding shotgun this morning )
large flight envelope and broad flying conditions.
Excellent flight times (9-12 minutes)

Upper wing ailerons would not hurt
requires landing gear design changes
Last edited by hilleardeng; Apr 06, 2016 at 04:25 PM.
Apr 08, 2016, 06:17 PM
I am a nice guy! Really!
Quote:
Originally Posted by hilleardeng
. . . -the wind had an average wind speed of 23km/h I guess gusting up to 30-35, it flew well it required minimum 3/4 throttle to head into wind and had to be pulled back on the down wind. . . .
One thing you should realize is that once the plane is airborne it does not care about wind speed. It may be moving fast downwind in relation to you but it's actual airspeed may be very close to a stall. You should be able to fly it at the same throttle setting upwind, downwind or crosswind. When you do as you did you risk stalling the aircraft especially when making a turn. This is the dreaded "downwind turn" problem that comes up time and again. People blame it on the wind, the airplane or the radio failing, but what it really is is the plane is flying too slow to stay in the air. In other words it stalls.
Apr 10, 2016, 02:53 PM
Registered User
HI mike your right, im aware of actual air speed, I just reduce throttle on the down wind so it doesn't go so fast, I just think it looks weird when the plane is going so slow one way then going insanely fast the other, this plane almost has no stall so its safe to do so, when it does stall it might lose 2-3m of altitude at the most. I run the throttle back up to 1/2 to 3/4 when making a turn after the down wind run then pull it back again when lined up into the wind for landing or leave it there for the run into the wind.
Fair point though and definitely worth mentioning.
Oct 23, 2017, 07:12 PM
Are they ever really "done"?
Hookdriver's Avatar
Awesome thread! Thank you for sharing it. Maybe I will finally finish mine. Maybe you said it already, and I missed it.... which motor/speed control/ prop did you end up going with? I built mine with ailerons on both wings. I built a mountain models EVA sport with the ailerons reflexed up on one setting. They made landings and some aerobatics a lot less work. Smoother inverted flight and excellent slow speed control. I think I might set my pitts up in a similar manner. Probably gonna start with a few degrees and work up. Four ailerons is a lot of surface area for spoilerons. Happy flying! Josh
Last edited by Hookdriver; Oct 23, 2017 at 07:45 PM. Reason: Spelling...