chorner

No problem, glad you found them to be helpful

j lauria

My UMS 9-99 seems to have very little compression when I turn the prop over. It is very smooth but offers little resistance to turning over. When I put it away last fall I went thru my usual routine of injecting after run oil and air tool oil as I did after each flying session. As I recall it had more compression than it seems to have now. As I get ready for the next flying season I would like to address any problems early on.

John

TimD.

My Feedback: (207)

Just needs some fuel or oil put through it. The rings will seal with minimal added. Also check that all valves are opening and closing correctly. Sometimes they will get stuck open.

TimD.

My Feedback: (207)

Hey Chroner, just curious how many hours have you been able to log on the 7-77 at those RPM's. I have always kept mine under 4600-4800 on the ground.

Are you saying that you run 6k steady on the ground? Wondering if I have been over proping mine. I have 4-5hrs on one and 1-2 on the other. I seem to have plenty of power and speed flying 32-34lb planes.

Sessholvlaru

Hi guys. I've read through most of this thread but could use a couple tips. I picked up a used 35cc Evo for a steal. It is already broken in. It's going in a Seagull Bucker Youngmeister bipe.

-What's the easiest fuel option? Gallon of 15% pink + a gallon of methanol (7.5% nitro, 9%oil)?
-What's the best after-run oil?
-Manua says fuel consumption is 1oz per min...I'm thinking a 12 oz tank.

Thanks!

Sessholvlaru

Well I already answered one question and ordered a few gallons from Ritches Brew.

-So what machine oil? Something in a precision dispenser would be nice.
-12 oz tank enough?
-And I'm reading that onboard glow isn't necessary. Can I run something external that I can unplug once it is running?

Maxam

My Feedback: (62)

On the 9-99, you are turning a 100cc prop against 11cc cylinder,one at a time. Will seem like low compression. Best oil is air tool oil. Running with no on-board glow is possible but good tuning is required. On the 7-35, use more oil with fuel like 10%. It is a delicate engine and do NOT let it run lean. 12 oz is good, these engines should not be run at full throttle constantly. -tom

Sessholvlaru

Need some help. The glow harness has a positive and negative with two banana plugs. How did you guys mount these? Not sure why they didn't put females on it.

Since mine is already well broken in, I'm not running onboard glow, so I just need to make up a NiCD pack with female banana plugs, right?

Dad_Roman

Yes......and you just answered your own "why are males on the plane" question.

Remember....1.5v is all you need......but lotsa amps.

Maxam

My Feedback: (62)

Well folks, a milestone with my winter build. I have the frame-up completed on my S2 models Sky Scout with the rare Seidel ST-540. This was a limited edition engine with only 300 made. Think of it as a 5 cylinder version of our 7-77 and 9-99's. The prop is true scale size and pitch. The middle shock portion of the landing gear is not inserted into the hole but will be. The instrument panel is covered with veneer from an in




dividual cigar container.

Dad_Roman

Very, very nice!

chorner

Hey Tim,

I've got about 7 hours on mine. Not a huge amount of time, but completely stripped mine recently and looks and runs perfectly fine for me. I think really the main concern of revving this engine too high is the chance of losing a pushrod. You have to adjust them carefully IMO. The internals of the engine (bearings, and materials) are high enough quality that revving up to 7,000rpm won't do any damage that's for sure... the bearings are very beefy as is the overall construction of the moving parts.

Just keep an eye on pushrods for any 'chips' and check valve lash. Again I don't think you'd want under 5,200-5,500 on the ground optimally for the engine from my experience anyhow. The engine's RPM is rated as 6,000 'max' (on the ground) in the manuals. I know the designer of the Hangar 9 60CC Corsair David Payne recommended running a 22x12 at 6,250 rpm approx on the ground as what he's found to be the best combination for the engine (7-77) and plane (posted here on RCU in the thread for the plane near the beginning)... and the 22x12 is one of the recommended props in the instructions as well.

I just don't think (as with any more expensive 4 stroke model radial engine you can buy) if you're after longevity you want to pin the throttle at full all the time. I do it for very short bursts while flying and on takeoff But having that reserve and a wider RPM range to work with when flying can be a good thing to have sometimes.

iamzoli

Hello Guys ... i just came in the possession of an 7-77
Question is it a problem if i fly it with an 3x20x10 i see recommended is 3x22x10 but i just have a beautiful scale 3x20x10 already

Dad_Roman

Technically it should work just fine. To move up to a three blade you need to bump one catagory or the other down one step, so, moving from a 22 to a 20 should do it.

Let the real world application and trials began

bcrc

My Feedback: (19)

Do the Evolution radials have an impeller or equivalent inside the back end to send an equal fuel mixture to all cylinders?

Maxam

My Feedback: (62)

No they do not. The do run rather evenly however. -Tom

cymaz

Maxam....

May I suggest some cross bracing on the cabane struts, and across the centre section. I've a parasol wing plane ( general western Meteor p 2 s ). And it stiffened up the wing a treat for very little weight gain

Maxam

My Feedback: (62)

Cymaz, if you look closely at the pictures there are tabs on the cabanes for cross bracing wires with turnbuckles from Proctor. All four sides will be wired including the tail group. Thank you greatly for your comments and Doc Martin and Downton Abbey! -Tom

Maxam

My Feedback: (62)

Dad Roman, Thank you glad you like it! Covering it now -Tom

cymaz

Looked up Pietenpol Sky Scout on the interweb. My there were a lot of variations. I suppose being a home build, anything goes !

blw

My Feedback: (3)

Maxam- it looks too good to cover

Maxam

My Feedback: (62)

Well, I DO plan to fly it! Thank you. -Tom

Pretendpilot

so, no need to add fuel tank pressure from exhaust pipe on 777 with os carb?

Maxam

My Feedback: (62)

The Sky Scout is finished!

TimD.

My Feedback: (207)

YES, use the pressure tap to give steady supply of fuel on either carb.