chasrb

I use the 99% pure methanol and Klotz as well in my Siedel ST710. I picked it up from a speed shop in Manassas park on 28 toward Centerville Va - For all you NOVA folks.

Use about 6% or so Oil. Runs great.

jr4350

Can someone tell me what the physical size - dia and dist  prop to firewall - of the asp radial is?
jr427

Ram-bro

My Feedback: (101)

I know it is here in the thread already......wish I could remember where

radial1951

jr

According to the attached chart, the OD [D] is 227mm. The distance from the firewall to the prop driver Dim. A is 159.3mm.

The relevant details are on the right hand side. It's not very high res, but is just readable.

Regards, radial1951

BobH

My Feedback: (2)

Do they sell Klotz there as well? Im guessing You use the Klots Techniplate to mix with the Meth?

SOUTHERNX

Hi and a Happy New Year to everyone,looks like Hobby King are tempting us radial engine enthusiasts with a price drop on the ASP400 five cylinder, now only $759.99.Now I need some words of encouragement from owners of this engine-still a little worried about cam gear and shaft wear, not to mention link pin failure, but what a price,and the Aussie dollar still up there,verrrrry tempting.

Sundownee

My Feedback: (30)

HI guys, I have this question around but still have not a answer that is going to be a yes or a no.

I am building a KMP AT-6 88 inch wing span, the new that just come out form KMP, I want to put a 7 cylinder radial in her, I like the Seidel ST7-35 it will spin a 18X8 at 5200 rpm, little over 2 hp.

the cowl (230mm width and 245 length- oval of course) is just perfect for this engine( engine is 187 mm), if it was alittle bigger like 1/2 an inch it would fit the ST7-70(engine is 235mm)

the 35 cc wieghts about 2.6 lbs and the 70 weights 5.9 lbs.

But am I going to have enough power with the ST7-35 to fly the AT-6 or will it just be alittle under power or ??

I could make a new cowl to fit the ST7-70 but it be will much heavier to setup and with 4 hp maybe too much power as it uses a 22X10 prop

thanks for you info
Paul

Dad_Roman

I was initially going to say no, but after looking at the Manf. site it looks like it must be a real lightweight.

They call for a 26-30cc so that 35 may be just the ticket. Probably wont "jerk" it off the ground but might be perfect for scale flight!

redball8

My Feedback: (128)

Sundownee,

I had the same concern about the UMS 735 - bottom line, it has to turn much more than 5200 rpm. Maxam (post 2664) ran his up to 7,500 rpm with an APC 17x8, which ThrustHP computes should give 2 Hp for 14 lb thrust at 57 mph. Only question is reliability - where does that 5,200 rpm limit come from? The larger engines?

Quote is from post 2519.

77chickenhawk

its a multi cylinder engine.. you don't need to rev the piss out of it.. goodness,, in my opinion they are under propping the engine spec's a muli engine has something a single cylinder engine doesn't have...torque

Sundownee

My Feedback: (30)

that is what I was thinking, A 7 cylinder 35 cc producing 2 hp but has way more torque than a singal ro daul cylinder engine.

Maxam I did not see your post that you had already run up your engine, but I was told that the program thrustHP shows power way under actual thing,
here is a program that is web based that I beleive is more in touch of actual reading with pitch and know hp

http://www.csgnetwork.com/directacthrustcalc.html

Do you have video of your engine running, would love to hear it run, I was going to purchase the engine today but needed to know for sure which one

He told me that I would get the new vesion of the 35 as it would be ready by middle of the month, but had to decide by monday as they are going to a large Distrib after that no more direct. so I think the price is going up.

I am going to weight the plane by istself to see what the total will be, I thinking with this 35 engine and all around 16 to 17 lbs.

Paul

radial1951

Sundownee

An 88" plane with only a 30cc engine?? The CMPro 83" Zero is just right with the Saito 325 5cyl radial. Thats 53cc. Also great with the OS 55 gasser.

http://www.youtube.com/watch?v=ulL3j3vZzNA&NR=1 I think there is also a video on YT with the ASP 5cyl 65cc.

The World Models 80" Zero is rated for 160 2stroke although the Saito and ASP 5cyl engines are on YouTube Videos. The video below shows the Zero with a Saito 170 3cyl.

http://www.youtube.com/watch?v=B5cMH...eature=related Not bad performance and great sound!

For my money the new Saito 200 3cyl would be the choice. It's on special at Advantage Hobby for $795. Known Japanese quality, spare parts availability, and IMO a better sound than a small 7cyl radial.

BUT i know what it's like when you want a 7cyl, then that's what you MUST have !!! (what do you mean when you say the cowl is "oval"?)

Regards, radial1951

Maxam

My Feedback: (62)

The number of cylinders an engine has vs what torque or rpm it should run is irrelevant. Many of the highest rpm engines are multi-cylinder. Not all radials are "torque" engines. Valve timing and degree of overlap are the main determinants of the ideal rpm vs hp and to a lesser degree bore vs stroke. Case in point. the Saito's are rpm radials and dramatically loose power when over-propped. They have "hot" valve timing and much valve overlap so they must run at higher rpms to develop reasonable hp. My 90-r3 has an APC 13/7 and flies my hangar 9 corsair solidly (300 flights and counting(8500 rpm). My 325-r5 swings a 20/10 xoar ok(6800) but should be swinging an 18x10(7500) for more performance and ideal running(big cowl though). The Seidels have much less sporty valve timing with little overlap and therefore produce their ideal power at lower rpms. This is also true of the Moki radials.
Now to address the ST7-35 and its larger models. I have been in contact with UMS but I never can talk to someone other than a salesman or manager. I do own the 9-90, the 7-70 as well as the 7-35 all of which I have run extensively to full break-in. I have tried multiple propellors with each engine. Remember these are glow engines and ignition timing is determined by the plug "temp" compression ratio and fuel mixture. Overloading these types of engines leads to high temps and detonation. The published top rpms for the Seidels are 9-90-6000 rpm, the 7-70-6300 rpm and the poor 7-35 only 5200 rpm!??? Each cylinder is only a .30 cu not the larger .60 cu of the bigger engines. This makes no sense whatsoever. So I tried to put a prop that would keep the rpms to 5200. Right. The poor engine ran under great strain with high temps on the cylinders, even when richened to an excessive amount. The onset of detonation was occurring. Very definitely overloaded. Folks this is really a tiny engine. Running it on the 17x8 it turned the higher rpm and was running cool and developing some power! This is very definitely not running the hell out of it. Loading it to 5200 rpm will beat it up. So what do we do? Run it with a smaller prop and limit the throttle opening to keep the rpm to 5200? Oh boy barely one measly hp out of 35cc, or load the hell out of it and still get no or little more power and ruin it. Both of my bigger Seidels are propped for the mid to high 5000's and run cool developing good power. Running the small engine at 7000 or so should not hurt it at all and be ideal. To answer the gentleman who wants to put it in the 88" plane, pass. Get it for a 60 to 80 size (cu in) plane. It is a fine running little engine. -Tom Maxam

Linkan2

Hallo Maxam
I will haw mi seidel 7-35 in a  Great Planes PT-17 Stearma.
I think dis will bi fine  or ???
Lars Lindstöm

radial1951

Maxam, a lot of good info there. Nice to see someone understands the effect of valve timing on rpm range etc. I admit I'm a Saito fan, not just for the engineering issues, but also because of the cam timing. It gives them a great sound flat out, a nice lumpy chatter for part throttle slow passes, and an idle that reminds me of a top fuel dragster!! (Ok, I'm a dreamer...)

I wonder if there is a mechanical strength issue that makes UMS want to restrict the top rpm of the 7-35? But as you say, the HP is a product of revs, and small engines can usually rev hard. Maybe 5200rpm is a typo!

Regards, radial1951

redball8

My Feedback: (128)

Running the 735 properly propped and limiting it to 5200 rpm makes no sense - strictly would be a display / demonstration piece.

If not a typo, the rpm limit on the UMS 735 struck me as some sort of mechanical limitation (ie, valves start to float). But Maxam, you can run it up to 7500 without such an issue, so the only thing left to my mind is excessive wear. This would be the case if the design or metallurgy is inherently limited, like the 770 and 990 which have similar limits. Unfortunately, wear might take some time to show up.

RB8

Maxam

My Feedback: (62)

Linkan2, Keep the plane light!!!! Use light wheels, servo's batteries parts. My hangar 9 corsair only weighs 7 lbs 10 oz which is why the saito 90-r3 can fly it well. And yes you will need to allow it to hit 7000 or so rpm.

Redball8, UMS said it was not a typo (again salesmen/managers). The much shorter stroke and smaller parts would equate to about the same mechanical speeds (piston speeds and accelerations) as the larger engines. The 7-35 does have delicate valve springs with low tension. No wear showing yet. The engine feels nice and "creamy smooth" when I turn it over and the compression is excellent on all cylinders. I just checked, the largest 250cc seidel is listed as having a top rpm of 6000! Everyone, sorry I do not have a video camera.

Dad_Roman

Hey Tom (and radial) if the manufacturer was recomending a 26cc on the low end then wouldnt the 35 be just about right?

They had the engine range as 26-33cc and they only offered a combo with 26cc. Of course I know they arent always right but it seems like the 35 might be nice in it.

I thought an 88" was to big for the 35cc too until I looked up the recommendations, now Im having second thoughts.

What do you guys think?

Sundownee

My Feedback: (30)

I just weighted the KMP AT-6 with, all the parts (fuse-wings-cowl-elevators-canopy-cockpit/hatch) it came out to 7 pounds.

the fuse is glass and all other flying parts are built up balsa and ply covered with coverite looking cloth weave, painted with decals.

I am very sure I am still going to try the St7-35 in her, the wings are 88 Inch long but the fuse is only 65 inch long, this was a training plane for the war.

Really love all the comments, ideas, etc I am getting here.

Paul

Dad_Roman

Paul, look in your literature and see if you can find us a "Wing Loading" number for this model.

If not, then look for the sq. inches of wing area and we can calculate the wing loading.

Linkan2

From the factory

Engine number S351210 010

Engine type  7-35 glow

Engine Speed
(low)   (high        1600  / 5500 RPM
Temp on cylinder head
60c  average
propeller  18x10

Sundownee

My Feedback: (30)

ok, the wing area is 1034 sq in and with my calcuations using help from online calulator, the wing loading is 33.424 oz/sq.ft

they state the flying weight is 14.9lbs but i just added alittle to even 15lbs

Paul

Linkan2

I haw no manual for the ums 7-35.
So i wonder of the fuel ??

Dad_Roman

Yea thats basically right and thats about the right wing loading for an AT-6.

I was hoping it would be a little less, in the mid 20's.

Its gonna be scale

Sundownee

My Feedback: (30)

ok, then that settles it! ST7-35 here we come, my first radial and i think more to come!!

thanks all for all your input and I will keep ya posted to the outcomne.

Paul